Can stress cause atrial fibrillation?

Generally, not. If there is no underlying cardiac problems that may predispose one to atrial fibrillation, it would be unusual for stress to be actual cause; however stress can be the underlying to so many maladies, that one never says never. If one develops atrial fib, must look for underlying heart disease, and--even it none is found-be treated for it by cardiologist specializing in cardiac rhythm disorders.
Yes. Yes it is possible, especially if the heart is damaged, or enlarged.