Mark Levin explained that a tie is the same as “not passed” and the measure is dead.
"Republicans have a 53-47 majority in the chamber, and can afford up to three defections when the Senate considers whether to call additional witnesses on Friday. In the event of a 50-50 tie, by rule, the vote on witnesses would fail in the Senate. Chief Justice of the United States John Roberts is likely to abstain rather than assert his debatable power to cast a tie-breaking vote."