From what I can see, Firestats is working correctly.
Dom's theory is one possible explanation for the discrepancy. Google Analytics collects a ton of data, which can be parsed in any number of ways. They have a bunch of algorithms for combining what appear to be discrete pageviews and visitors. It could be that something like this is happening here.
It could also be that Google is being smarter about not counting non-human visitors. Search engines and other bots may crawl a site many, many times per day. Firestats should be ignoring these hits (and in most cases, it appears to be attempting to do so), but it's possible that it's being outsmarted by Google in this case.
Another thought is that GA's results are misleadingly small, because Google isn't being properly pinged on every pageload. For performance reasons, we put GA tracker code at the bottom of every page, and it typically doesn't phone home until the entire page is rendered. Thus, very short pageviews may not be consistently tracked by GA. Firestats, on the other hand, loads in the head of the document, and so will not miss this kind of pageview.
In any case, it's not practical to expect that these kinds of stat counters will be very accurate, given the variable nature of pageloads on the internet, and unclear definitions of what counts as a "hit". The best use for such tools is relative monitoring: you can't really compare GA to FS on a given day, but you can compare today's FS stats to yesterday's.
Unless there are objections, I'm rejecting this ticket, as everything seems to be working as expected, and no action need be taken.