First, we've got population. The world today has 6.8 billion people. That's headed up to about nine billion. Now, if we do a really great job on new vaccines, health care, reproductive health services, we could lower that by, perhaps, 10 or 15 percent.
https://www.ted.com/talks/bill_gates_innovating_to_zero/transcript?language=en
It does if you consider Gates has claimed that increased health results in fewer people having children. Whether or not that's accurate or it's just a lie to push his evil agenda it follows logically and is a perfectly valid explanation that isn't "Bill Gates wants to murder everyone." (Which is true, but not because of these random quotes he's said in public appearances. These quotes prove nothing on their own.)