You can do that right now though. Just ask.
Here's all about brand deals from
two Youtubers.
You want to know about ad revenue? For most sites, like mine, ads and editorial never meet. I believe our ads are handled by our parent company, Gamer Network, but I never see or hear anything about whoever handles them. When the ad takeovers (when the entire site is one big ad) pop up, I'm as surprised as you are.
As I said previously, that's how you end up with things like a full Borderlands: The Pre-Sequel ad takeover, while our review is a 2.5/5. We don't talk to them, they don't talk to us.
I believe most sites operate in the same manner, but that would be up to others to confirm.