A 4 year old child has 16k wake hours x 3600 s/hour x 1^6 optical nerve fibers x 2 eyes x 10 bytes/s = 1^15 bytes (approximation by Yann LeCun).

Unfortunate typo. You meant 10^15 bytes at the end.

Thanks to your citation I was able to find a podcast transcript [1] with Yann LeCun's explanation:

If you talk to developmental psychologists and they tell you a four-year-old has been awake for 16,000 hours in his or her life, and the amount of information that has reached the visual cortex of that child in four years is about 10 to 15 bytes.

The transcript is missing "the" (10 to the 15 bytes). The corresponding timestamp in the podcast on YouTube is 4:48.

[1] https://lexfridman.com/yann-lecun-3-transcript

[2] https://www.youtube.com/watch?v=5t1vTLU7s40