I'm sad to say that short of replacement, I've never found anything that will completely remove fuel from carpet. Worse yet, if you don't get the carpet out, the fumes will permiate the other fabrics in the interior.
I picked up a Pinto Wagon back in the day that I put a V8 in. The previous owner had spilled gas in the interior a couple of weeks before I got it. It was nasty. Even after I replaced the carpet/pad, which made it a ton better, it took months to air out to the point that it didn't gag you. It had cloth seats that were in great condition, this was an upgrade over vinyl. I didn't want to replace them. I pulled them out to thoroughly clean, and had the windshield out while I built the engine and painted the car. Probably sat open for a couple of months, it had quite a bit of time to air out.
We scrubbed, pressure washed, steam cleaned etc., it was tough. It got to the point where you didn't mind being in it but you still knew it was there. It was the equivalent of standing in a clean service bay. In retrospect I probably should have replaced the head liner.
If you could lay your hands on an ozone generator I've got to think it would be worth a shot.
I'm interested to hear if others have been more successful in this endeavor.
Man that was a quick little sleeper. Those were the days.