Yes, both the character Rocky DeSantos and the actor Steve Cardenas are of hispanic extraction.
However, Rocky is very americanized and showcases little knowledge of hispanic culture, to the extend of making people wonder if he is truly hispanic.
There are some non-hispanic people whose surnames sound hispanic, i.e.: Ariana Grande's last name sounds hispanic, but Ariana IS of italian extraction.
EDIT: Many so-called hispanic characters in the 1990s were very americanized. This phenomenon happen in other TV shows, not just Power rangers, i.e.: Maria López from Saved by the Bell-The New Class and Lorena Acosta from California Dreams.