Certainly the failed vote would be good for Rand Paul but not Trump.
I think Trump realizes this which is why he came out with this after it was announced that such a vote would fail:
Trump says time to 'let ObamaCare fail' after health bill stalls (By Alex Pappas July 18, 2017 Fox News)
I don’t think a repeal failure will reflect on Trump. Everyone knows the rino CONgress is at fault. Trump can use his twitter to point out who voted to keep Obamacare, and the voting anger will be directed toward the rino’s. This will help him clean up CONgress a little.