They're all composites of several families and real people.

There's no way the DiMeo family is based entirely on the DeCavalcantes, not with the power they have, although a lot of season 1 was certainly based on the Decavs. David Chase himself said a lot of the Sopranos are based on Richie The Boot Boiardo's crew, that ran Newark when he was growing up in the 60s. That's a Genovese crew.

A lot of law enforcement thinks Tony is based on a certain Lucchese guy in Jersey. Forget his name.

I think the only real DeCav representation was the war between Tony and Junior in season 1, which was undoubtedly based on Charles Majuri's war with Vinny Palermo. An acting boss, dying of cancer, appointed the ruling panel instead of giving Majuri the throne, which he felt he deserved.

The Gambinos had a lot of influence on the Decavs in the 80s and 90s. I'm sure the Lupertazzis are based partly on the Gambinos. Phil Leotardo's complaints about how Jersey doesn't make guys the right way were similar to things Gotti said.