GameSeek (a U.K retailer) is already taking pre-orders for Grand Theft Auto V. You can see the release date i.e November 22, 2013 as claimed by them. The game costs a mere £24.75!
The listing can be seen here http://www.gameseek.co.uk/pd/VideoGamesycs65a12qv/Grand-Theft-Auto-5-GTA-V
On the other hand, DevBuild who is a Reddit user has said that Rockstar is already testing the PC port of Grand Theft Auto V and he’s one of the testing team (Rockstars Toronto). Not much has been revealed by him but a few screenshots