Bill Gates Says Vaccines Reduce Population 4 Times

Vaccines mean healthier children, and healthier children leads to a reduction in the number of births a family living in a high-childhood-mortality-rate region will have so that some of their children survive.

He's talking about reducing childhood mortality and population growth, not reducing population outright.

If someone can't tell the difference between "reducing population" and "reducing population growth" then I don't think they're qualified to opine on Bill Gates' motives.