I went looking since I've heard that claim.  It was an Economist-YouGov poll, and the finding was 35% of Trump voters hold a view of Putin that is somewhat to very favorable.  It's not fair to say this number is representative of the Republicans since not all Trump voters are members of the party. It is however, very disturbing to think that any American would think well of the man.  Especially any American holding public office.  

https://today.yougov.com/news/2016/12/14/americans-and-trump-part-ways-over-russia/