I don't think it works like this: a fixed rate times the number of streams. It is probably the other way round. They get _some_ revenue per user per month, which can be ads or a premium fee (which again can be different, because there are student, dual and family subscriptions, as well as one time promotions). Then they get their cut. The rest is divided between thousands of copyright holders according to some magic formula. Spotify still gets its 30%. As long as their operating cost to serve you is less than 3.33 EUR, they are good.
If you listen 3000 songs and pay 10 EUR, I suppose that will pay out 7/3000=0.002 EUR per song. 5 times the average. If I pay 16 EUR for a family subscription, and we listen 100 tracks, then I suppose our streams will pay out 16*0.7/100 = 0.112 EUR per track. That's crazy good (at least I hope that the artists I listen to get that much from my streams when I don't listen much). My friend listens to Spotify Free. Let's say the ad revenue is 1 EUR per month. 0.30 is the cut. 0.70 goes to the artists. If she listens to 160 tracks, it will be close to the average Spotify pay out. Not much. Better than nothing.