As your friend entered the U.S. without being iadmitted by USCIS officials at the border or other port of entry and he gained entry through presentation of false documents then this complicates matters.
Your friend will not be able to apply for Adjustment of Status which is the process whereby one applies for permanent residence without leaving the country as your friend's entry was unlawful.
There is possibly one exception to this rule known as I-245, which enables a person to adjust status despite having entered unlawfully so long as they meet certain criteria, among which is having been the beneficiary of an immigrant petition or labor certification application filed before May 2001 by a U.S. employer or U.S. citizen or lawful permanent resident relative.
If your friend cannot adjust status, then the only way involves your friend returning home and then reentering the U.S. on a new visa obtained in your friend's country, which is potentially a dangerous path for many people who have spent more than 179 consecutive days in the U.S. following an unlawful entry. In many of those cases, departure from the U.S. triggers a three-to-ten-year bar from returning, for which a waiver is often available but cannot be pursued before the departure.
My suggestion would be for your friend to consult with an immigration attorney.
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