I'm talking about if there is a massive power outage, for several days or more. I've always wondered what they would do.
Well, let's use the massive power outage of 2003 as a guideline...with no power for a few days, businesses were shut down and people didn't have far to go, so pumping gas was a minor issue, but a few gas stations were equipped with generators for those who had to fill up.
to answer your question without going around it like generator crap . . . siphon like ty said and just measure it out gallon at a time. then charge price from there. not too hard. things are simple if you make them simple.
You have back up generators that provide electricity? Otherwise I guess you could siphon it, not a long term solution.