Can hair gel cause hair loss?

Unless you are using a very harsh/poorly made gel, probably not. But if you suspect your hair gel is the culprit you can always try switching to another more gentler brand, or stop using it altogether. Better yet, talk to an expert to help diagnose the cause. 

Gels or other products that used for hair string does not cause hair loss them selves unless you have a concurent hair loss of androgenetic or other type .