“Welcome back to the Ziegfeld, Mr. Grey!” said an enthused usher to “Cabaret” star Joel Grey when he arrived at the theater for an anniversary screening of the film, which debut there in 1973. The touching moment made one die-hard fan of the Bob Fosse film burst into tears on the spot. Also expected at the celebration were the musical’s original stars — Liza Minnelli, Michael York and Marisa Berenson — who all appeared earlier yesterday on NBC’s “Today.” The film dominated the Oscars 40 years ago with 10 nominations and eight wins. Minnelli said on “Today,” referring to the unlikely hit, “I could hear people whispering, ‘Well, how are we going to advertise it — the nifty Nazi follies?’ ”