Yes maggots can kill a cat if they eat enough of the maggots.
The maggots can cause bacteria poisoning in both humans and cats as well as other animals when they eat them.
Any food that contains maggots including cat food, dog food, human food etc should be thrown out and discarded and not eaten or consumed.
If the cat does eat maggots then they could get very sick and start vomiting, have diarrhea, stomach pain and other health issues.
Then eventually the cat could die of the maggots because of the bacteria poisoning.
Maggots are fly Larvae that has likely been in contact with poop because flies love to land in poop and lay there eggs in poop.
So the food can contain those traces of the poop or other bacteria that the flies landed on.