How much income do I have to have to apply for my husband who's currently living in a foreign country?

Requirements about documentable income relating to a petitioning spouse in an immigration application/consular processing depend upon such things as geographical location and family size. The current requirements may be found here: https://www.uscis.gov/i-864p. Of course, there are many other details that relate to eligibility for a spouse located abroad to succeed in getting immigration benefits. There really is no substitute for you and your fiance 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.