A search for renewal was done in contributions to publications and in artwork for the years 1958 and 1959. There were no listings for the name "Ella Cinders"; there's no evidence this is still under copyright.
Date
January 25, 1931 Copyright 1931 Metropolitan Newspaper Feature Service
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.