Less money and more time. Assuming you have people that will do it for fun. And I also do mean a LOT of time. Gtav took about 4 or 5 years, so I'll give OP a min of 10-15 years.There's quite a few things wrong with your idea OP...
You need a lot of money to even consider taking on a game such as GTAV.
You need a very large team, also branching off the money aspect.
You can't just be an ideas guy, many developers I know, myself included hate people who try to be the ideas guy. "Add this, add that! People will love it!".
Also... *whole
Less money and more time. Assuming you have people that will do it for fun. And I also do mean a LOT of time. Gtav took about 4 or 5 years, so I'll give OP a min of 10-15 years.