In Russian, Катя (“Katya”) is the most common diminutive of Екатерина (“Catherine”).
Being subject to pogroms as well as official discrimination, Jews apparently assumed conventional Russian names as disguise. For example the family I’m trying to reconnect were branded “class enemies” in the time of Stalin, so they moved from Kiev region in Ukraine to Omsk, Siberia and changed the surname from Kagan (Cohen). I heard this chapter of family history from “Aleksandr Mikhailovich Suvorov” which is about as Russian a name as one could possibly invent!
Emigrants to America apparently have felt freer to be more openly Jewish.
