There are a few simple rules to find out the expectant life span of an animal. One of the general rules it that a larger an animal is, the longer its life span. This is based on the fact that the smaller animals have a faster heartbeat rate and their bodies are high releasers of energy, so their bodies wear out faster. So a cat will have a life expectancy that is longer than a mouse. There are exceptions to that rule. Take for example that larger breeds of dogs have a shorter life expectancy than small breeds of dogs. Since all domestic dogs were developed by humans then breed genetics would play a larger part than natural selection would.
Another rule is that cold blooded animals tend to live longer than warmblooded animals of the same size. That is why tortoises tend to have very long lifespans.
There is a limit on size versus life expectancy. Whales, for their size are not the longest lived on animals.
One last rule I would like to mention is litter size and short gestation. Animals that have large and frequent litters have shorter lifespans than animals that have long gestation periods and single offspring.
Of course there are always exceptions to those rules.