When I begun doing YouTube a few years ago I was told to use 1000 viewers = $1 as a baseline rule but then it vary a lot with your niche and the location of your viewers. Some niches pay a lot more others a lot less and adds in some contrary are a lot more expensive/cheaper than other.
My channel is in the gaming niche. During 2016 I was making $0.88/1000 views, during 2017 I was making $0.9/1000 views, during 2018 I was making $1.05/1000 views and last year, 2019, I was making $1.36/1000 views. As you can tell the amount of money I get from 1000 views have been increasing each year and from the start of 2020 it looks like the same will happen this year.
To compare the effect of viewers location, last year I was on average making $3.5/1000 views from Australian viewers and $3.3/1000 views from American viewers. Compare that to viewers from Indonesia that was $0.34/1000 views and from Turkey that was $0.21/1000 views. $3.5/1000 vs $0.21/1000s that's an insane difference. That's $350/month vs $21/month if you channel have 100k views/month. So if you really care about the money there is a lot to be gained by making content that interest people in high paying nations.