After reading about Bill Acosta, I recall seeing a very good impressionist named Andre Philip Gagnon at, I believe, the Venetian many years ago. Robert Goulet, who was one of his voices, was sitting the crowd. Whatever happened to him? He was outstanding, but appears to have disappeared from Vegas.
André-Philippe Gagnon is a well-known comedian and singing impressionist from Quebec, a.k.a. "The Man of 1,000 Voices." He specializes in impersonating such celebrities Frank Sinatra, Elvis, Elton John, Mick Jagger, all four Beatles, Louis Armstrong, James Brown, Barry White, Tracy Chapman, Ed Sheeran, Justin Timberlake, the Black Eyed Peas, Pharrell Williams, and literally hundreds more. His big breakthrough was in 1985 at the Just for Laughs Festival in Montreal, where he performed an incredible routine doing the voice of every single singer (18 in total, including Michael Jackson, Lionel Richie, and Bruce Springsteen) on the famine-relief anthem "We Are the World." He later reprised the performance on "The Johnny Carson Show."
Gagnon is 63 years old. He was born 1962, in Loretteville, Quebec. He did his show at the 1988 Calgary Olympics opening and has hosted awards shows in Canada many times. He had a decade-long residency in Las Vegas, starting in the late 1990s at the Venetian, where you saw him, then moving to the Paris showroom; he was a major draw in both venues. At the time, we reported that he was the first Quebec comedian to perform on the Strip for extended stints.
As you also say, he did disappear from Las Vegas. We couldn't find any dates here in decades. Nor did we unearth any major news, like new albums, retirement, or controversies. He appears to be steadily performing, dividing his time between tours and private functions for organizations around the globe.
If anyone has seen or heard of him recently, we'd like to hear about it.