No.
Geordi was not supposed to be gay, and Roddenberry did not plan to include gay characters until later.
I come to this conclusion because
- several key persons never talked about this
- it was not in "The Bible"
- the TNG Head Writer left the staff because of a conflict which would have gone very differently if Geordi had been planned as being gay
- It has been announced that Season 5 would include gay characters, without any mention of any plans around Geordi
Several key persons never talked about this
If Geordi would have been gay, or even been planned as gay, there are several people who would have mentioned it. Granted, there's always the possibility that they either did not know or had other reasons not to mention it - but there are several occasions where, if Geordi would have been planned as gay, they would have mentioned it.
It was not in "The Bible"
David Gerrold, who also happens to be gay, was a writer for TOS, and was brought to TNG to set up the foundation of the new series. He was heavily involved in creating "The Bible" - the Writer's and Director's Guide.
He also wrote a few articles for the "Starlog" magazine, giving us insights on how the Bible has been created:
(Source)
To sum it up, Roddenberry created an initial "bible", all writers contributed to it until Gerrold prepared it for Roddenberry, who finally rewrote most of it until the document was done.
Gerrold also gives us insights on the early drafts of LaForge, but other than his blindness, doesn't give us many details (If you are interested, here is the issue). His sexuality is not brought up.
Gerrold also specifically mentions that they want to avoid discrimination during casting, and that they don't want to have someone being gay just for the sake of being gay:

(Source)
The relevant quote is:
If we were to approach the casting of this show as a kind of ethnic Mulligan Stew, we would be committing the very same kind of discrimination that we are trying to say will not exist in the future. "Now, let's see, we need a woman, a black, an Asian, an Indian, a Russian, a gay person, an alien, an android and a child - did we leave anybody out?" That's the kind of thinking that reduces people to caricatures and stereotypes. Gene Roddenberry's thinking is to find interesting human beings and take some time exploring who they are and why they are so interesting.
In the light of this statement, it would be at least odd to have Geordi being blind, black and gay at the same time.
Anyway, the final Bible does not contain any references towards Geordi's sexual preferences:

The TNG Head Writer left due to a conflict which would make a lot less sense if the claim was true
The same David Gerrold stated in an interview how Gene Roddenberry said that it was time to have gay people on the Enterprise:
So now Gene and I appeared at a Star Trek convention in November of 1986 and somebody asked “will there be gay people aboard the Enterprise?” And Gene – to give him credit for knowing the right thing to say at the right time – said “yes, it is time, we should show gay people on board the Enterprise.” This got a lot of applause. So then he repeated it in a staff meeting and balled out one of the producers and said “no, it’s time”
(Source)
Because of this, Gerrold submitted a script that actually included gay characters, but he faced stiff opposition by other writers such as Rick Berman as well as Roddenberry's own lawyer:
So Gene’s lawyer sits on Gene’s face for a while – he was another homophobe – and said “you have to take the gay characters out.” And so I give half the lines to Tasha Yar, because if we still get the episode on the air, the point will still be made. And we go through rewrite after rewrite after rewrite and the script doesn’t get any better and I see what is going on and I don’t want to be trapped in an office where we have hypocrites running the place.
[...]
Rick Berman writes that we can’t do this episode and how we are on at 4PM in some markets and mommies are going to write letters. We get half the staff saying we shouldn’t do it and the other half – those who could recognize a good story – saying “this is a hell of a script, we got to do this and demonstrate we are the Star Trek that everybody’s been waiting for.”
Gerrold then let his contract expire and left.
Had Geordi been gay at that point, this whole conflict would not make any sense. And in his capacity as the Head Writer, Gerrold was there when the foundations of TNG have been built. Therefore, if there would have been any "early TNG script" in which Geordi would have been gay, Gerrold would have known. The whole conflict would have played out much differently if the statement was true.
And for the record, the story Gerrold submitted did not include a gay Geordi LaForge.
Gay and lesbian characters were announced for TNG - but for Season 5
In 1991, it was announced that the next season (Season 5) would include gay and lesbian characters:
This season, gays and lesbians will appear unobtrusively aboard the Enterprise in the 24th Century. They weren't "outed," they won't be outcasts; apparently they'll be neither objects of pity nor melodramatic attention. Their sexual orientation will be a matter of indifference to the rest of the crew.
This article also mentions at no point that there have already been plans to have gay characters in TNG. Roddenberry died in 1991, and his plans to include gay and lesbian characters seemed to have died with him.
Bonus points
- TNG: Booby Trap features Geordi falling in love with a female hologram. That episode aired before Roddenberry's death