I've heard that JKR is both a Gryffindor and a Hufflepuff, so I'm not sure what to believe.
Has J. K. Rowling revealed the house into which she was sorted, and has her answer been consistent?
In 2000, J.K. Rowling took a random fan-made sorting quiz that she stumbled across while trying to understand what "the internet" was. She got Hufflepuff.
The Internet! Twice I've been on the internet. Friends of mine were telling me what's on there and I'd never gone looking before. First time, I thought I was never coming back, it's too scary. Some of the stuff that's out there is very weird. Second time I went in there someone had set up an unofficial fan site where you can be sorted, they have a Sorting Hat, and I was Hufflepuff. I wasn't that pleased! If anyone's meant to be Gryffindor, it's me.
Eleven years later she made her own quiz, so she could get the house that she wanted.
Scholastic: We polled some of your fans and we asked them what question they most wanted you to answer. Close to 40,000 people voted and the question they selected with 40 percent of the vote: Which Pottermore House are you in?
J.K. Rowling: Well as I say, I know how it works. So I logged on, and I’m now on Pottermore as a regular user – that’s how I go check what’s going on – although I’m not going to give my user name. So I went through the Sorting, and I am a Gryffindor. But I had a moment as I clicked the answer to the last question – and bear in mind, I wrote the questions – I thought, “Hey, I’m not sure if I’ve answered to get Gryffindor.” I answered them completely honestly, and I knew that I’d answered a couple for different Houses so I thought, “I wonder how they’re going to work this out.” Yes, I am in Gryffindor.
J.K. Rowling was Sorted to Gryffindor..
I logged on, I’m now on Pottermore as a regular user. That’s how I check what’s going on – even though I’m not going to give my username. I went through the sorting. I had a moment… I thought, ‘Hey, I’m not sure if I answered the questions, I answered honestly, to get me into Gryffindor.’ But yes, I am in Gryffindor.”
Rowling reveals in an 1999 interview that she isn't a wizard:
Am I a Muggle? Yes, I am definitely a Muggle.
A Muggle with abnormal amount - er - of knowledge about the wizarding world.
Her answers about believing in magic also confirm that she's a Muggle. First in another 1999 interview:
[…] Did you believe in fairies and magic?
I don't believe in magic in the sense that I write about it, but I do believe that extraordinary things can happen in the world for which we don't yet have an explanation. […]
Then confirmed in a 2003 interview:
I really don’t in magic the way that it appears in book. I could be slightly corny and say I do believe in other kinds of magic; the magic of the imagination for example, and love, but magic as in waving a wand - no. I’d love to believe in it but I’m afraid I can’t.
Thus, J. K. Rowling isn't permitted to go to Hogwarts and won't be sorted to a house.