According to an article in the Scotsman today, so called "industry experts" are predicting that GTAV should bring in over £1 billion ($ 1.56bn) for Rockstar, by selling 25 million copies in its first year. The game has a development and marketing budget totalling £170 million, an absolutely massive amount for a videogame, so it doesn't take a mathematician to work out that this will mean a huge profit for Rockstar.
There isn't really any new information in the article, it does however state that the game world is 49 square miles (78km2) which, if true, shows just how massive it really is. The majority of the article talks about the game from Scottish perspectives, given the game's roots in the small country. It touches on the sheer amount of detail that goes into making the game. Read the full thing over at The Scotsman.