It never came up at Gotti's trial; I know that much. On direct he was only asked if the family approved drug dealing while he was in the administration, which he demurred (they technically *didn't*, y'know, but it's not like they ever investigated anybody either, and if a capo or two came up short in their weekly payments, that was a personal problem they needed to resolve). And since it wasn't raised in direct examination, the defense couldn't bring it up in cross examination. The closest they could get was trying to intimate that Gravano was on drugs himself at the time of his testimony (who knows?).

Gotti and Locascio both tried to raise the drug thing on appeals, and basically got laughed out of the circuit courts. The real world, unlike the Mafia world, tends not to care so much when a multiple murder turned Federal witness might have sold heroin too. Also, until he fucked it all up by still being what he was all along, Gravano was a huge propaganda piece for the Feds. It was a way of both striking fear into the bosses (causing more potential crimes, which could be recorded in the planning process and entered into evidence in a Federal courtroom), and letting underlings, even guys who might have been involved in as many as nineteen murders, know that the federal government would treat them fairly.