How long can it take my husband to get a green card and will he have to leave the country?

Significantly more information is needed in order to assess eligibilities, options and strategies for your husband. This includes, for example, knowing whether you are a U.S. citizen; when and how did your husband enter the U.S.; what applications have been filed by or for him before; etc. There really is no substitute for conferring with an immigration attorney who, after learning all of the relevant information, could provide advice and offer legal representation.