In a case where no candidate has a majority of Electoral Votes the house votes by state, not by individual members. Each state in the U.S. House of Reps gets 1 vote, meaning there are 50 votes (D.C. would not be able to vote since the Constitution specifically mentions states). Right now I believe Republicans control 26 states as far as Republicans having a majority of members in that state’s delegation in the U.S House.
It would actually benefit Trump if the House determined the Election. And that is actually a Trump firewall if Dems totally screw up the Electoral system.