FPS rate and bottleneck

My system specs
Intel pentium g2030
Corsair vengeance 8gb ddr3 ram.
And i wanna buy a gpu so which one should i buy a gtx 750ti or 1050 and which one gives the better performance
 


Resolution will have no affect on CPU performance, vice versa. Very few settings actually affect the CPU load, those ones like View Distance and FOV. The other graphical settings are purely dependant on the graphics card.

So the answer to your question is it plays, just at 30 - 45 FPS with lots of stutter . If you want more bearable gameplay in GTA V you'd need to upgrade the CPU.
 




With that cpu even a GTX 1080Ti will not run that game at a playable FPS. If you want to run GTA V you will need a better CPU to go along with either of those GPUs.