I'm pretty surprised that the GTA / Lindsay Lohan thing keeps coming up. It's pretty easy to find the real model with google and heaps of other comparisons of real woman to the poster.
An IGN podcast a few years ago joked that Rockstar was going through their staff - the poster in GTA4 supposedly looking like Jessica Chobot and the GTA5 poster looks a bit like Naomi Kyle. People also thought it was Kate Upton.
Do Rockstar just turn up to court with a pictures of thousands of women who kinda look like the poster?