A trusted comic site, Bleeding Cool, believes they know who the prominent gay DC Comics character is. They say it's Alan Scott, the Earth 2 version of the Green Lantern.
Here is the scoop from BC writer, Rich Johnston
I ran semi-sourced stories indicating that the character who DC Comics announced as being reintroduced to the New 52 DC Universe as a gay man, was Alan Scott, the original Green Lantern, who appeared in Earth 2 #1 briefly.If this is the case, then the hype was just hype. Alan Scott? I hope they have a good story if this is true.
Well, at Phoenix Comic Con, I had a much stronger source confirm to me that, yes, it is indeed Alan Scott. On that basis I feel confident in calling it. Keep your Earth 2 #1 in good nick, and start queuing up for Earth 2 #2… right about now.