TBH the quality of the camera lens and sensor are at least as important as the number of pixels.
My old 4 MP Canon G3 produces far better pictures than some brand new 5 MP cameras.
Yes, you will just about see the pixels at 5 MP and 11x8 but only from a distance of a few inches. If you aren't making fine art, 3 MP or more will be fine. Even 4MP @ 11x14 is acceptable for a wall-mounted framed picture from my old G3 - although the pixels are obvious if someone peers right up to the glass.