So, I've been thinking about this, and I realized that the only reason people thought this was because of Eidos is that Gerstmann was fired on a day that Kane and Lynch ads had been skinned to GameSpot. Despite this being pure conjecture, the internet decided that this was the reason Gerstmann was fired. All evidence points elsewhere. Yes, the video review was pulled, but anonymous GameSpot staff have said that this was because of quality issues, namely a bad microphone, Gerstmann being late to the taping, and footage of only the first level. The review of Kane and Lynch was indeed edited, but the edits were mostly to add in differences in the PS3 and 360 versions. Beyond that, there's nothing otherwise to suggest that anything having to do with Kane and Lynch or Eidos had to do with Gerstmann being fired.
There's evidence the other way, though. We've got GS's staff's opinions that the video he was in was low quality, partly due to lack of punctuality. We've got that his review didn't contain information GameSpot deemed was necessary. We've got that he was fired a long time after the review was written, relatively, and that the deal for the website skins was made a very long time in advance, as well. We've also got that GameSpot's employees think he was fired after the holiday rush of games, and consequently, not because the website was skinned at the time he got fired. That's several pieces of evidence that suggest he wasn't fired because of the Kane and Lynch ads, compared to a few poorly drawn conclusions and conjecture that says otherwise.
I'll take my evidence and pass on the hysteria.