Of course it has bearing. A FF 50 mp camera will have about the same resolving power as the 7D II.

The 7D II advantage isn't the crop it's the pixel density.

If we are getting a 20% gain with the 7D II, you would get the same with a FF. The difference is you get it across the FF pic and the FF benefit. I bet the high ISO performance will be lacking though.

As far as resolving ability, my makeshift tests were using arguably Canons sharpest lens, the 500mm II.
I wonder if 50mp will be well above any lenses ability.