In the book backstory in which Luca killed his child and his child's mother, there are references to Luca's gang of ruffians.

There are also book references to Luca's people , when he met with the Capone gunmen and "convinced" them not to interfere with the NY wars.

So in the book he had some followers but I doubt they were very many. In the movie we don't see these folks.

Movie or book, Luca's value to Vito was that "he could do a job of murder all by himself". So Vito would not have needed (wanted?) him to maintain a crew.

Since Luca's primary job was killing, torturing or intimidating people I don't think Vito would have wanted to waste those talents by having Luca worry about how much to bribe this police officer, or if he laid off enough money for that book this week, or whether or not this person was ready to be a formal associate or Family member. Those were the jobs of Tessio and Clemenza.