Are there gay characters in my books? Of course -- because there are gay people in the world. My books reflect reality.
But am I a "gay writer"? Well, I'm gay and I'm a writer but I don't see myself as a "gay writer", in that it's not the main thrust of my books. They are sci-fi or horror, not gay. But in most of my books there will be gay characters.
Of my first three books, two contain gay characters and one doesn't. As for the one that doesn't, it's not that I said, "Oh, I think I'll leave gay people out of this book." It just so happened that the characters I visualized for that book were straight. That's because there are also straight people in the world, and I have no problem with straight people. They're fine.
Gay people, trans people, lesbians, and bisexuals will never be portrayed as "lesser than" in my books. Equality is my middle name. Respect will always be shown to gay-related issues.
One of the helpful things about science fiction is that by definition, it pretty much always takes place in the future. In terms of gay people, this is great because I can jump to a world where gay people are not considered odd at all. In my third book, two of the main characters are a man and his husband. It's totally normal in the book because it's 2030. Anti-gay stuff is a thing of the past in America, with the exception of outlying, little, pointy heads here and there.
I like the idea of presenting gay characters as normal people, and that's what I do. Until a day comes when we're considered a regular part of the human race (and we're not there yet, not at all), then I think it's important to present positive images of us all.
I think my tally so far is that I've got two main gay characters in one book, along with a trans character, and in another book, there are two main gay characters. That's a pretty solid showing for gay people, I think.
But they're far outnumbered by straight people in every book -- because that's the way it is in the real world. I like the real world. So in the end, I don't think I'll be seen as a gay writer, though certainly as a gay-friendly one. That's fine with me.