"Enough expository banter! Now we fight like men, women, and women who dress like men! For Gilgamesh, it's MORPHING TIME!" - Gilgamesh
It was confirmed months ago that Gilgamesh will appear in the upcoming prequel/sequel of Dissidia: Final Fantasy, Dissidia 012 [duodecim]: Final Fantasy. Just recently, his first official appearance in the game that is not game artwork or smoke has surfaced!
So far, we have no additional info about Gilgamesh in Dissidia 012, asides that he will appear in the game as part of Chaos' group, collect some swords and still owns some Genji Equipment... which you can still in the original Final Fantasy V game!
Source: Dorocia via Siliconera