To answer, you'll have to explain what it means for a set of pixels to have a "cellular makeup as [in] a living person". Your question doesn't really follow based on my earlier tounge-in-cheek (but factual) statement about pixels vs. proteins.

Perhaps you're asking about the eventuality of finding a living person that bears a strong resemblance to one of the generated images. That would depend on a totally subjective observation, and you would always be able to take any number of photos of the alleged real subject showing discrepancies with the generated one.