Rockstar Games has just released an official guide on how to change language in Grand Theft Auto V. The language in GTA V depends on your console language setting.
If your console language is not supported in GTA V you will be prompted to select a language when starting the game. If you would like to reset the language after the game has already saved it:
- Command to Change Language in GTA V on Xbox 360: Hold LB + RB while booting the game
- Command to Change Language in GTA V on PS3: Hold L1 + R1 while booting the game, or clear your game data (NOT save data) from the PS3 Game Data Utility in the PS3 XMB (system menu).