How much income is the requirement to sponsor my wife?

The documentable income necessary to sponsor a spouse in an adjustment of status application process depends upon such factors as the sponsor's family size, state of residence, etc. Here is a link to the information you need: https://www.uscis.gov/i-864p. If you do not have sufficient documentable income, then it may be necessary to have joint sponsor in the application process. Generally, a joint sponsor may be any U.S. citizen or Permanent Resident who has sufficient documentable income and who is willing to assume the responsibilities contemplated in the Affidavit of Support document. Of course, there are many other details that determine eligibility. It would be wise for you and your wife 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.