From Dave Meltzer via FightOpinion:

There was no “$30 million” offer, although if he won the championship, the sport continued to draw and he was a major draw, he could have earned more than that. UFC wanted a six fight deal, but offered three fights, figuring it would be an easier deal to conclude since Emelianenko’s side would see it as him being locked up for less time. They offered on 7/28, about a $2 million guarantee, plus a sliding percentage based on PPV buys. The first fight offered was with Brock Lesnar for the championship. If the show did 800,000 buys, a huge disappointment considering Lesnar’s status right now, Emelianenko would still come out of it with well over $3 million. If it did 1.5 million buys, he’d get more than $5 million, the biggest one-night payoff in the sport’s history.

It’s worth noting that Dave Meltzer is considered something of a holy MMA scholar amongst the hardcore news junkies to the point where many actually pay to read his MMA news even though it’s sandwiched between pro wrestling obituaries and the latest Bam Bam Bigelow news. So these are pretty reliable numbers.