Answer by taking a quote from the following article:

Cimino was born in New York City on February 3, 1939. A third-generation Italian-American, Cimino and his brothers grew up with their parents in Old Westbury, Long Island. He was regarded as a prodigy at the private schools his parents sent him to, but rebelled as an adolescent by consorting with delinquents, getting into fights, and coming home drunk. Of this time, Cimino described himself as "always hanging around with kids my parents didn't approve of.

Interviews with Cimino were rare; he declined all interviews with American journalists for 10 years following Heaven's Gate and he gave his part in the making of that film little discussion. George Hickenlooper's book Reel Conversations and Peter Biskind's highly critical book Easy Riders, Raging Bulls deal with the film and resulting scandal. Hickenlooper's book includes one of the few candid discussions with Cimino; Biskind focuses on events during and after the production as a later backdrop for the sweeping changes made to Hollywood and the movie brat generation. Steven Bach, a former UA studio executive, wrote Final Cut (1985), which describes in detail how Heaven's Gate brought down United Artists. Cimino called Bach's book a "work of fiction" by a "degenerate who never even came on the set". However, Bach's work does discuss times in which he did appear at the shooting location to confront Cimino about the budgetary issues. While Al Pacino, Meryl Streep, Francis Ford Coppola, Gene Hackman, Sidney Lumet and Robert De Niro all gave interviews for the 2009 John Cazale documentary I Knew It Was You, Cimino refused to do so. However, the European DVD release of The Deer Hunter contains an audio commentary with Cimino as does the American DVD release of Year of the Dragon. In 2011, the French movie critic Jean-Baptiste Thoret wrote a large profile on Michael Cimino for Les Cahiers du Cinema. Cimino appeared on the cover. In 2013, Thoret published in France an acclaimed book, Michael Cimino, les voix perdues de l'Amerique (lost voices of America). Flammarion. ISBN 978-2081261600

What did he have to do with the movie The Deer Hunter?
In 2013, Thoret published in France an acclaimed book, Michael Cimino, les voix perdues de l'Amerique (lost voices of America).