what is the minimum amount of content does model need to make money and what is average.
This greatly ranges based on business model. Some models' main asset is content, for others it's interactions (comments, messaging, live streaming), and for some even lack of interaction - like for BDSM mistresses - in ignoring the poor sods that get off from being ignored

So, it's hard to say what the requirements are. We require that the model uploads 1 video and 1 photoset during setup steps to learn how to do it (they may choose to delete them right after.
can we see sample sites with approximate revenue?
I'll be happy to give you some site examples, but revenue stats is up to site operators - models - whether to share it or not.
We've recently announced the launches of
Dani Daniels | Splash and
Eva Lovia | Splash - so that's two of the most recent well-known additions to MC.
Natalie K posted in this thread and she runs a website powered by MC -
NatalieK | Splash
Here are a few of the other models I work with and recommend for promoting:
Dominika-c | Splash
Lysadiction | Official Page
http://dirtylittleholly.com/
http://ginagerson.xxx/
http://sam38g.com/
http://ibizaluci.com/
http://kyliecupcake.com/
http://vipbrittany.com/