How long gerbils live depends on a number of things, such as how they are kept and what species they are. Mongolian gerbils that are kept well and who have everything they need can expect to live for anything between two to five years, whereas fat-tailed gerbils will generally live for anywhere between five and eight years.
Which species of gerbil you have will have a big impact on how long they live for
Some gerbils that are kept very well may lead quite short lives if they fall ill from something such as a tumour or a stroke, but in general gerbils are quite healthy creatures. Just be sure to keep them clean, give them regular health checks, and give them all the vitamins and minerals they need to thrive.