I know that Moff Delian Mors (a lesbian woman in the excellent canon novel Lords of the Sith) is the first LGBT character in Disney canon, and Sinjir Rath Velus (from the abominable canon novel Star Wars: Aftermath) is the first gay man in Disney canon. Also in Aftermath, there is a lesbian couple - Esmelle and Shirene.
Another casual reference to a minor gay character referred to only as Ledaney appears in the brilliant Star Wars: Bloodline:
“You sure you’re doing okay over there, Seastriker?” shouted Ledaney, who was fixing up his own X-wing a few meters away. “Or do we need to fetch you some soda water and a fan?”
Guffaws echoed from every pilot in the place. Joph had made the mistake of being honest about his reaction to Port in a Storm, which meant he was going to spend the whole day hearing about it from guys who’d never once tried drinking the stuff.
So he shot back, “I’m good, Ledaney. But what about you? Word has it you’ve been hitting the Corellian stuff pretty hard lately.”
This time the laughter was louder. Anybody who didn’t know Ledaney would assume Joph was talking about the famed brandy, but every pilot in the squadron knew Ledaney’s new man was from Corellia.
- Star Wars: Bloodline by Claudia Gray
And unofficial though his statement was, Oscar Isaac attracted attention when he said he played the part of Poe as though Poe was romantically interested in Finn:
“I think it’s very subtle romance that’s happening; you have to watch it a few times to see the little hints. At least I was playing romance; in the cockpit I was playing romance."
- Oscar Isaac on Ellen
Similarly, Mark Hamill said Luke's sexuality is in the eye of the beholder:
“If you think Luke is gay, of course he is."
- Mark Hamill, quoted in Time Magazine
However, Mors, Velus, and Ledaney are canonically LGBT characters, but Luke and Poe's sexual orientations are as yet unknown.
Are there other characters in the franchise who are confirmed to be LGBT?
Note: Although I'm not aware of any pre-Disney LGBT characters, and I'm primarily interested in Disney canon, Legends is acceptable as well.