It can still be smelled in one spot if you put your nose to it.
OK, this reminds me of the patient who keeps poking himself in the eye, and tells the doctor "It hurts when I do this", and the doctor replies "Then don't do that".
As gasoline is a volatile, it will eventaully all evaporate. However, it will stink pretty bad in the meantime. Soap and elbow grease.. and go buy yourself a new gas container for next time.
I have to say, it's awful when you spill something in the back of your car. A few years ago I was coming home from a "Chain Home Improvement Store" with a gallon of paint on the floor behind me. Went around a corner, heard a clunk, thought nothing of it. I get home, go to take out the paint, and see it oozing out of the bag all over the footwell. Talk about going into a panic! I got out my shop vac and the garden hose and spent the next 45 minutes or so soaking my carpet and sucking out the water. I got it all out, but one of the trim pieces on the seat rail had to be replaced, I just couldn't get all the paint off it.
That being said, I wonder if this might work for you: lots of soapy water and a wet/dry shop vac.