No, just having a muscular body type and a male voice does not automatically make Snowflake "Male". Plenty of Gems have muscular body types, and voice doesn't determine gender. Gems don't have gender. Yes, it'd be possible for a gem to use he/him pronouns if they chose, but voice alone isn't enough to go off, and we don't know enough about the character yet to concretely know if they deviate from the general rule of all Gems using she/her pronouns. Especially since Snowflake has most likely not been around humans long enough to understand the use of he/him pronouns, between Homeworld, the war, and the short time they've worked on the boardwalk.
voice =/= gender.