Yes. Trump can make Mexico pay for the wall and it will be easy

A 10% tax on immigrant remittances would do it.

Yes, you read that correctly. Immigrant remittances received by Mexico have surpassed Mexico’s $23.4 billion in oil earnings. This means the government of Mexico is more dependent than ever on the earnings of maids and gardeners in the U.S. to keep itself afloat. This is the leverage Donald Trump talks about to pressure Mexico to pay for the border wall.
Trump’s proposal carries: the border wall solution, the employment solution, the enforcement mechanisms of current law, and another angle that is strategically essential. “WESTERN UNION REMITTANCES” (Money Services Compliance)