Based on my personal experience - yes, 2 GB of VRAM will suffice.
I've been playing with a Radeon HD 7850 2 GB and the game runs surprisingly smooth. Yes, obviously, my graphics settings are turned down a little bit but I am able to play just fine with my available VRAM.
Also, according to their website, the minimum required AMD graphics card is a Radeon HD 7730, which has only 1 GB of VRAM.
Edit: Sorry, you'd care about the NVIDIA card... The minimum required is an NVIDIA GeForce GT 640.