Undocumented? How did he enter US? Sure, you can file a relative's petition but he can't adjust his status here and he will be barred from admission for 10 years after departure unless the I-601 waiver petition is granted, and that will be based on extreme hardship to you. Who knows what your situation will be in 7 and a half years. If he entered on a B-1/B-2 visa and falls in love with a US citizen and will be reciprocated in his feelings then he has a chance.
1. You file USCIS form I-130
4. It may take forever, since he will need a waiver and the waiver grant is not guarantied.
NYC EXPERIENCED IMMIGRATION ATTORNEYS www.myattorneyusa.com; email: firstname.lastname@example.org; Phone: (866) 456-8654; Fax: 212-964-0440; Cell: 212-202-0325. The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter.
1. file form I-130
4. However long it takes for the priority date to become current. The movement of priority dates cannot be predicted.
For the latest visa bulletin see http://www.engnishimura.com/priority-dates/current
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature and does not constitute legal advice, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship. Answers on Avvo can only be general ones, as specific answers would require knowledge of all the facts. As such, they may or may not apply to the question.