Elliot, who plays Bobby in "Nace una estrella", wins a Golden Globe on Sunday, has a career of more than half a century in film and television.
"The people you work with, the community, be a part of it, the connection with the fans, feel like you're making a difference," said the 74-year-old actor AFP about the joy this job gives him.
Elliot said, according to the theater's Twitter, that before entering the show, his hands and feet were in cement because he worked as a worker.
Gaga quickly came to an embrace shared by Elliot and Cooper, director of the musical drama, sounding strong for the Academy Awards.
"We were deeply concerned with the relationship between these brothers and the father, and raised the issue of addiction, love, somehow it was very deep for me and deeply moved me," he said.
"We love you, Sam," wrote Lady Gaga on Instagram.
Elliot was nominated for the Golden Globe for "Conagher" and "Buffalo Girls", who also earned him an Emmy nomination.