If the card was a stolen card, I highly doubt it would be able to use it more then a couple of time over the course of an hour or two at the max.
Gas pumps have been the easiest place to validate a stolen credit card works. There is usually no attendant (NJ is the exception) so if it is flagged a s stolen the perp can just drive off. When a card is reported stolen, the first thing to check is gas purchases. This is why you have to enter your zip code at the pump now.
BTW: I'm not a professional credit card thief. I work at a large bank in network security and have worked with customer satisfaction and fraud.
Most likely, the attendant is paying at the pump using his credit card and using the cash to pay off his credit card. If he is using the Disney rewards card then we might see him in Disney World soon as he can rack up some major Disney Dollars in a hurry. I would think that the gas station would not consider this acceptable and if the credit card company were notified, would revoke the points.
If he pumps 5 $40 fill ups an hour, over the course of a year, he would charge a total of $416,000. $4,160 in Disney Dollars would be nice little vacation each year.