How many natives prior to European influence?

Answer 1

1491: New Revelations of the Americas Before Columbus is a 2005 non-fiction book by American author Charles C. Mann about the pre-Columbian Americas. The book argues that there is evidence accumulated over the last several decades suggesting that human populations in the Western Hemisphere — that is, the indigenous peoples of the Americas — were larger in number, had arrived earlier, were more sophisticated culturally, and controlled and shaped the natural landscape to a greater extent than had been previously thought.(Wikipedia)