It depends on what you consider "work".
They are certainly not in physical exercise for anything close to 40 hours a week. They spend more time in the gym during the summer than during the season, which is largely spent in maintenance mode.
There is film study and chalk talk in hockey, but not to nearly the extent that one would see in the NFL for example. They review their prior games, get some video on tomorrow's opponent, and move on. They are not spending hours and hours in meetings.
On a typical day they spend an hour or two on the ice outside of gametime. It depends on the schedule, but a morning skate is standard.
Games of course run about 2.5 hours, bearing in mind the players show up to the rink hours beforehand, and leave perhaps an hour after the end.
Combining all of the above, I'd arbitrarily say they spend 4-5 hours a non-gameday on work related activities (workouts, film training, skates). On gameday that jumps to more like 6-8.
The big hidden factor is travel. When they leave the arena, they head to the airport and take a 3-hour flight, then head to a hotel. That might be a 6 hour process all together. During that process they're maintaining their bodies in terms of nutrition, sleep, injury treatment, etc. Is that "work"? If so, the number of working hours gets much larger. In a certain sense, one could argue that they only get a few hours a day truly away from their training, where they're not eating or sleeping or exercising or being coached.