Well, you can't say LFS is really very active these days. Nor is it or has it been very influential. The total number of subscriptions doesn't mean much, considering that a lot (most?) of these people don't play LFS anymore, or play it once per six months.
The fact is that at the moment of writing this post, there's 1454 racers online, only 901 of which are licensed. And that's at 2:21 PM EST, which is close to peak hour, if not peak hour itself. That's not really a lot of people.
In my opinion, a game that can be considered influencial is a game that is not only at some point the best of its time, but also almost flawless. Therefore, even if at some point LFS probably was the best sim, it was never completed, or even near completion, and always had things that were simply not up to date (i.e. graphics).
However, there might some elements of LFS that could be deemed influential. For instance, the physics are probably still the best (I don't know how they compare to iRacing's) and overall the multiplayer experience is pretty much flawless compared to other online games I've played in which lag and other issues were much more present.
All of that is, however, besides the point for Scavier. It's a known fact that they don't really care what others might think of their product, and just want to keep working on it the way they currently do. This is quite arguable, as I personally believe that a completed LFS S3 updated to 2008/9 standards graphics and other points that are lacking could very well be a better game than iRacing.