In that they are both part of the rodent family, yes, though there are many differences that exist between the two, like coloration, habitat, the way they eat, etc.

yes they are related

Squirrels and chipmunks both fall into the "Squirrel family" in the rodent order. Others in this family include prairie dogs, woodchucks, and marmots. There are more species of chipmunk than squirrel.