Unfortunately there is no provision for IEC participants to bring a spouse or partner with them. And, as you likely know, IEC is not normally open to Americans. (Though, it’s worth noting, there are exceptions.)
Because your husband is American he could attempt to get a job in the US and then get transferred to Canada (it would take a while and must be a skilled job). Otherwise, he will have to look for work, get an LMIA and a work permit like everyone else.