According to IRCC website, if your husband has a TRV or eTA then he will be permitted to travel with you. But if he plans to travel at a later date after your arrival to Canada then he needs a written authorization in order to be permitted to board a plane.
Yep, is what it is stated on the web age. We decided to take the risk, so he is traveling with me on December 23rd. I'll let you know how it went =).