There are a lot of rumors out there about the next version of GTA. But, the closest to confirmation we’ve seen so far is this resume from stunt driver Declan Mulvey. He lists his involvement with all the movies and video games he’s worked on and GTA V is one of them.
Some think that it would be easy to forget the I before the V, which we can understand. But, his name is nowhere in the credits for GTA IV. While we have known about GTA V for a little while, this certainly shows that further development has taken place.