how many pixels does the human eye have
It is wrong sense of calculation of human eye perception.
as you mentioned the human eye just sees the image but the actual creation of image is done in by the nerves, nuerons of the brain. So the picture what we see and the clarity is not a term which could be calculated in terms of pixels as pixels are calculated in a mage created by a single entity or system, but here it involves many parts of the body. In the creation of a human face the eyes, nose,mouth, cheecks, eyebrows, etc are stored in different parts of memory. so these parts are brought to a centralised place in the brains by the neurons and a made as a picture and the person is interpreted as XYZ. All this takes place in few nanosec.
So pixel calculation is not done for the image created by the human brain. ya but many websites give theories and explaination, but if we find the correct meaning of the word pixel, and understand the neuron activity in brain, these websites expalination are all false.
More over image pixel does not depend focus of lens, but human eyes power changes when ever it has to create an image or the factor of shortsightedness and longsightedness caomes into picture for pixel calculation.