CPM is around $1, or $1 per 1000 Ad impressions. Clicks I have seen as high as $0.25, but its going to vary on the Ad shown obviously.
Essentially my rough guide on income per active user per day based on my very limited experience:
Assuming each user will go through 10 impressions per day/play session. About 10 minutes spent in your game, this is a pretty big assumption and highly game dependent.
100 active users = 1000 impressions per day = $1
1,000 = 10,000 = $10
10,000 = 100,000 = $100
100,000 = $1,000
1,000,000 = $10,000
So on and so forth, just a rough guide. But it will HIGHLY depend on your own game and how long they spend playing it per session. For me, when I had my game free + Ads/IAP, I see per active user generate around 10 impressions per day.
Flappy Bird was said to have about $50,000 a day from Ads. It had about 50M downloads (probably heaps more down since everyone rushed to get it before its gone!!), probably had 10M active users (lots try it once and uninstall or never play it again). I would guess the "average" active user plays it a few minutes per day only.
Also my guide is probably inflated, since if users disable mobile data or wifi, no Ads are ever shown. To be safe, double the required active user