I think it's safe to say that that has a lot to do with it.
Ryechu: Affiliation assumes that people from one moribund forum will want to join another forum with reducing activity. It may cause a spike in activity for a couple of months, maybe, but the activity will inevitably go back to how it was. You see how many newbies stick around these days, after all.
Ideally, the best way to fix it is to get rid of the ads and start an EoFF-wide campaign to recruit newbies. Or bring Cid back. Or make an internet time machine that takes us back to when the forums were more active. Let's face it: like Del said, the owners are pretty passive and don't do much (being generous here); so if anyone wants to shell out the money to buy the site, I don't see things changing.
However, I think Final Fantasy is in its downfall, and the members who once graced this forum with their activity have either grown up or moved on. The amount of activity will inevitable reduce in the end. I hate to be pessimistic about it, but that's the long and short of it.