The answer to whether 107 billion people have ever lived is Yes, according to one experienced Senior Demographer (with more than 40 years experience in his field) who works, and writes for the Population Reference Bureau named Carl Haub.
He published a, by his own admission semi-scientific, paper in 2011 entitled How Many People Have Ever Lived on Earth? which he begins by explaining:
Any estimate of the total number of people who have ever been born will depend basically on two factors: the length of time humans are thought to have been on Earth and the average size of the human population at different periods.
For the first factor he indicates:
According to the United Nations Determinants and Consequences of Population Trends, modern Homo sapiens may have appeared about 50,000 B.C.
and for the second:
Guesstimating the number of people ever born, then, requires selecting population sizes for different points from antiquity to the present and applying assumed birth rates to each period.
For the purposes of this exercise, it was assumed that a constant growth rate applied to each period up to modern times. Birth rates were set at 80 per 1,000 per year through 1 A.D. and at 60 per 1,000 from 2 A.D. to 1750. Rates then declined to the low 30s by the modern period.
The daily mail dutifully reproduced the authors data table
source: daily mail
Until someone invents a time machine, and has the inclination to go back and census roughly 108 billion individuals, I'm not sure we're going to get a much better estimate. Is that Khan with a double N, sir