"It would probably cost each team at least around $150 million (all figures U.S.) to operate without fans for a season, factoring in payrolls, travel costs, team employees, league dues. It’s believed some have told Bettman they would be financially better off not playing."
link: https://www.thestar.com/sports/breakaway_blog/2020/11/30/nhl-talks----or-lack-thereof----have-the-familiar-feel-of-a-lock.html