Lucianne.com links to a
Breitbart article which indicates all but three Republicans senators, for a total of 50, have cosponsored a bill condemning Nancy Pelosi's impeachment-lite process in the House. If that is an indication of how they'd vote on an impeachment, it would be defeated handily as passage requires a supermajority of 67 out of 100.
What isn't entirely clear is whether the 50 oppose the unusual process chosen or the fact an inquiry seems not warranted, perhaps there are some of each opinion. The three holdouts are reported to be:
Sens. Susan Collins (R-ME), Lisa Murkowski (R-AK), and Mitt Romney (R-UT)
The party loyalty of these 3 senators has been spotty for some years.