List specs. GTA 5 is a12 year old game.
Gpu is not the only thing that runs your games smooth, VOTV is kinda CPU intense too and its made on Unreal Engine 4, maybe you see lo-fi textures and think the graphic is "HalfLife level" but it's not, it has a lot of advanced lighting/shadows and a lot of physics calculation too. Being in alpha stage, consider that the whole game is just poorly optimized for obvious reason.