I'm not sure what Trump thinks he's doing here, supporting DACA would gain him no votes and lose many. He often words his tweets wildly, he is inexact in speech and words to put it mildly.
He could be trying to use DACA as a negotiating chip but there should be no chip. I really hope is not doing the Reagan thing of amnesty in exchange for building a wall/greater border enforcement, the Democrats and RINOs will just make that part toothless again.
Already 15 or more states have sued the federal government over this, they seem to take it as a sign DACA is dead. Simply amazing that Paul Ryan can find all the time in the world to take up this issue, which does nothing for real citizens, but he time to cry over illegal aliens.