I love Daniel Tosh, even since his stand up days, lol. He's so racey, but I just love the delivery of his jokes and just how quirky and creative he can be. Although, his sexuality, I am not sure.
I honestly think, with how much he jokes around with them NOW, that he continues to do so just to poke more fun at the people criticizing that his show is "so gay!". Back in his earlier episodes and stand ups, while sexuality jokes were addressed, it wasn't really a defining aspect of his act. I think he just likes to poke fun at everyone and keeping himself an enigma, which he does very well by balancing the "gay" things he does on the show with seemingly, stereotypical "straight" mentalities.
So, for all we know, he could be straight, curvy, upside down, sideways up. I'm not really questioning it since sexuality is very fluid to begin with, so, he may lean toward one or the other or a bit of both. I have the feeling though he is -mostly- straight and just plays along because he couldn't really care less and just likes to have fun, keeping people guessing.