I'm not entirely sure how one could even measure this. H181 has single handedly brought in thousands upon thousands of readers, and collectors over the years, truly magnifying and expanding the popularity of comic book culture to a perpetual degree. It's a massive snowball that keeps growing. Wolverine is a key player that helps keep the comic book world alive, which is exactly why H181 IS as important to the industry.
To be fair, I almost don't even think the comparison should be made, because we're talking about indie comics, and mainstream comics, which are two very different worlds.
I'm not saying Cerebus didn't have an important role, but to say that it's role was more important to the industry than H181 really makes me scratch my head.