[DuncanWaring]

Here’s a paper that makes a claim for 54 million.

https://uwpress.wisc.edu/books/0289.htm

Others make claims as low as 8 million, others say 100+ million.

I don’t see that the exact number is important; the original claim is that most were killed by diseases their immune systems had never seen.

[Nifster]

And that is an unknown. It does however fit the white guilt approach to history