Saw a post today in TIL that claimed that. Wikipedia says he ruled for 21 years. That would mean about 2 million per year. Seems rather hard to believe considering the weapons available at the time.
The median estimate is around 30 million for China alone. There were elements of the Mongol military that wanted to turn all of Asia into pasture for their horses and saw the annihilation of settled people as a logical first step towards that goal.
Most sources say something along the lines of "the population of central Asia declined by 30-40 million people during the Mongol invasions." This doesn't mean that the Mongols killed that many people directly, however. Rather, these estimates are the cumulative effect of armed conflict, disruption of trade, destruction of the food supply, disease brought on by malnutrition, etc.
This link has a good summary of the various estimates: http://necrometrics.com/pre1700a.htm#Mongol