Yes, GTA V is available for Mac.
Yes, GTA V is available for Mac.
The main concern is understanding the reasoning behind choosing OSX, and why wait another decade for a refresh or update, especially with a mobile release expected soon.
It doesn't work directly on OS X. The Mac release of GTA V is likely years away at best... During boot camp he'll face challenges maintaining a stable frame rate (likely struggling to exceed 30fps), but you can always adjust the settings to their lowest level. I concur with what was said—FirePro isn't designed for gaming; it can run games fine, but its performance is comparable to a basic mid-range GPU of today.