<https://www.britannica.com/story/why-is-the-mona-lisa-so-fam...>
<https://www.wikiart.org/en/marcel-duchamp/l-h-o-o-q-mona-lis...>
Google's Ngram viewer suggests a further increase of references in print following 1980, though that might reflect a disproportionate presence of academic works within the scanned corpus:
<https://books.google.com/ngrams/graph?content=Mona+Lisa&year...>
Leonardo seems to be very famous in his time and after, and he died under the patronage of the king of France. I highly recommend reading his notebooks, it gives a glimps of the mind of this genius. His observational skills were impressive. In a way he was a hacker if you take the expanded meaning of the word: always thinking up new things and inventions.