"He didn't rob nothin'. You know why he's dying? He's gonna die because he refused to come in when I called."

Did Marlon Brando mumble those words in "The Godfather"? Or was it Paul Sorvino in "Goodfellas"? Robert De Niro in "The Untouchables"?

The author of that particular snippet of tough-guy dialogue is actually John Gotti. It comes not from a screenplay, but from an evidence tape that was played in open court yesterday in Mr. Gotti's murder-and-racketeering trial in Brooklyn. The confusion is understandable, since there has been a symbiotic relationship between Hollywood and organized crime ever since James Cagney imitated the Chicago mobster Dion O'Bannion. Or is it since Joey Gallo as a young thug in the schoolyard practiced Richard Widmark's chilling laugh from "Kiss of Death"? Blurring Brutal Fact and Glamorous Fiction

John Gotti, famous for his expensively tailored suits and smug defiance, and whose taped conversations are sometimes accompanied by melancholy background radio music ("Mona Lisa") that sounds like a movie soundtrack, has blurred the line between brutal fact and glamorous fiction more than anyone since Al Capone. Or is it since Paul Muni played a Capone-like character in the 1932 movie "Scarface"?

Some law enforcement officials sourly maintain that Mr. Gotti stole his persona from the movies. "Did you see 'The Untouchables'?" asked one Federal prosecutor, who insisted on anonymity. "I think he thinks he is doing De Niro's Al Capone."

On the other hand, the screenwriters who created the movie "Married to the Mob" researched the part of its boss, Tony (the Tiger) Russo, by observing Mr. Gotti in court during his 1986 racketeering trial. "It was the way he swaggered around the table, his incredible confidence," said Mark R. Burns, who co-wrote the script with Barry Strugatz.

"It's a chicken-and-egg situation" said Edward A. McDonald, a former Federal prosecutor who played himself in the movie "Goodfellas." "Is Gotti imitating the movies, or are movies imitating Gotti? It's probably a little of both."

Take Salvatore Locascio, the son of Frank Locascio, a co-defendant in the trial who is accused by the Government of being the underboss of the Gambino crime family. Young Mr. Locascio, who loyally attends the trial every day, was outraged early on when Judge I. Leo Glasser disqualified one of his father's lawyers. "This is America; haven't they ever heard of the Bill of Rights?" he said angrily as he stormed across the marble floors of the courthouse. "We have a Bill of Rights in this country. It's right over there, on the wall. Tell them to go over there and read it."

Then consider: "We have a Constitution in this country. The Constitution -- ever heard of it? I suggest that when you go to your office you read it." Those words were spoken by Rod Steiger while playing the title character in the 1959 movie "Al Capone."

Books have been written about the attempts of organized crime to infiltrate the entertainment industry in the 1930's and 1950's. But there has also been much creative collusion.

Mobsters, tough and flashy, are an irresistible subject for Hollywood, and few mobsters can resist the allure.

"The Godfather," a 1972 film, came off as a paean to organized crime. That, as Nicholas Pileggi wrote in The New York Times Magazine, was in part because Joseph Colombo Sr., then the boss of the Colombo crime family, magnanimously agreed to aid the filming, provided some of his people were hired as extras and the word "Cosa Nostra" was not used. The actor James Caan, who played Sonny Corleone, spent so much time hanging out with Carmine (the Snake) Persico that undercover Government agents briefly mistook him for an aspiring mobster. Romanticized Lives

"It's clear from the tapes we've made over the years that movies have had an influence," said Douglas E. Grover, a lawyer and former prosecutor in the Organized Crime Strike Force in Brooklyn. "They play their roles with bravado. The lives have been romanticized by Hollywood."