At the moment, GTA V isn't out on PC, but I'm going to say that you'll need to upgrade to a GPU with at least 2 - 4GB and your ram could do better, the CPU on the other hand should be fine handling that..
Yeah you'll need a new GPU if you want to game at anything above low settings and even then i might be a stretch. i could be wrong but i think you'll be due for an upgrade if you want to play GTA 5 next week when it launches.