Vanity Fair has a nice interview with Jaleel White, who played Steve Urkel on Family Matters:
Is it true that you were originally cast as Rudy Huxtable on The Cosby Show?
Yep, that’s why the character was named Rudy—it was intended to be a boy.
OK, I’ll confess: Largely due to the Cosby Show, I had never known before reading this that Rudy was a boys’ name. I mean, I noticed men like Rudolph Giuliani going by “Rudy,” but since I grew watching the show, and didn’t know any Rudys in real life, I just thought it was a girls’ name, or a name used for both sexes.
Reading the interview, I figured that at the very least, some girls would be named Rudy as a result of the show. Wrong.
“Rudy” has never been a top-1,000 girls’ name.