Nobody is going to officially sponsor ESF, no matter how popular it becomes. Why? Because, let's face it, this mod is copyright violation at the very least and illegal at the very worst. Funimation don't seem to mind while it's free, but the minute a sponsor appears and says "I'd like you to advertise my product in your Half-Life mod", Funimation will emerge like a vampire from the shadows and demand either a cut of the profits or the total destruction of ESF as we know it.
So far ESF has avoided the wrath of Funimation, not even needing to borrow that cute little legal warning that DMZ has. Don't pretend for a moment that Funi don't know ESF exists. They have people whose job it is to know this sort of thing. Be glad they're benevolent - trying to find sponsors for 'borrowed' copyright material will test their patience.