An ssd will not improve fps within a game, it will improve the overall feel / speed of windows and loading games as a result.
I'm not suggesting it will btw

Not sure have a page file on the SSD would be a very good idea though? could decrease your SSD lifespan quite quickly?
Anyway... gone off topic: No, I really doubt you'll 'need' a 6970, but it would certainly last you longer. I would go for what you can comfortably afford, and uprate some other parts that might be lacking.