Salary paid employees working more hours for less

My husband has been working at this job for a little over a year. They just moved him to salary about 4 months and doing that cut hours. Noone has been able to get more than 36 hours a week. Right before Christmas they were told that they are letting 6 employees go. Since then they have been getting about 50 to 60 hours a week and being that he is the only one left on salary he is only getting paid the 36 hours, everyone else is getting paid hourly with time and a half with overtime. Is this legal? He is woking between 10 to 15 hours a day and only getting paid for 36. We need this extra pay. Especially since he's not going to have a job after January. Every little bit helps.