Ratskinner
Adventurer
Define huge...
I dunno if it counts as huge or not, but I do recall seeing (IIRC) Mearls briefly mentioning the influence of the Forge on their thinking. I got the impression it was viewed more as an awareness, rather than axiom. At the very least, I think its safe to assume that any prominent designers or authors in the field are at least cognizant of the "indie" thinking, even if they aren't "forgites". Which, honestly, I think is a good thing. If somebody is going to spend all that mental energy and time dissecting the hobby and its practice, it'd be a foolish designer who'd ignore such conclusions entirely...even if its just to avoid repeating what you may view as mistakes in their reasoning or designs. So how could you count that? If you were to discover that some part of 4e, say Skill Challenges, was devised under the influence of some Forge thinking/games, how many units of impact/influence/whatever is that?
Having said that, the real problem here, of course, is that none of us actually know who is doing what in their home games. So many of the indie games are available for cheap or free in electronic form, and I've personally witnessed much explicit "piracy" of pdf files.* Even if the games themselves aren't being played, its impossible to know how many, how much, or how often they influence people's houserules or hacks. Witness multiple discussions in multiple places about adapting FATE's aspects to some version of D&D or another. And again, how would you even account for that? If you could discover that there are 500,000 people playing otherwise standard d20 with aspects added in, how many units of influence is that?)::shrug::
In the end, this is totally subjective. Much like when people try to compare the changes between each edition to determine which edition marked the greatest change....its senseless to rank qualitative differences this way.
*Which, in this case, I can't see any moral justification for.