If I am a US citizen and my husband is under DACA, can I fix his situation?

The process is relatively easy if your husband can prove he entered the US legally. If not, then it is not so easy and a waiver is needed. It is not easy at all if he had prior deportation/immigration history.

Significantly more information is needed in order to provide a legal analysis of ways your husband may be able to attain immigration benefits, ultimately resulting in becoming a naturalized citizen. There really is no substitute for you and your husband to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.