It is safe to say that the conservatives and leftists are more anti-Le Pen than pro-Macron, and they represent about 40% of the population according to the first round of the election.
Considering that Le Pen gained only a few extra votes compared to the first round, it can be said that about 2/3 of Macron's supporters in the second round are not pro-Macron but in fact anti-Le Pen.