Harry Enten doubts it. He says Latinos don't vote based on immigration policy:
The fact is that even if immigration were the big issue, there probably isn't room for Obama to improve his standing against Romney among registered Latinos. According to the Pew poll, 20% of Latinos identify with or lean toward the Republican party; 67% identify with or lean to the Democratic party. That's why it's not surprising that Obama led Romney 68% to 23%. For Obama to pick up any measurable support from the Latino community, he would need to win pretty much every independent voter, or start flipping Republicans. That seems unlikely, given the relative unimportance of immigration to Latino voters.
Nate Silver sees the policy as an attempt to boost turnout rather than win new Latino voters:
Mr. Obama’s decision could motivate some additional turnout among these voters. If, for instance, Hispanic turnout increases by 5 percent, and 5 percent of Hispanics who might otherwise have voted for Mr. Romney now vote for Mr. Obama instead, it would swing a net of about 1 percentage point in support to Mr. Obama. That is hardly a game-changer, but it could matter in an election that could be very close.