How similar are Turkish and Arabic?
Would it make sense to study some Turkish as a stepping stone to learning Arabic?
From what I know they share some vocabulary but that's the only advantage you would have since both languages have completely different roots.
As a Turkish native speaker I can say no. They have common words but different structures. Turkish and other Turkic languages are Altaic languages while Arabic is Semitic language. For Arabic starting with Hebrew would be better however for Turkish you can start with Korean or Japanese maybe Finnish.