Le Pen’s situation is far different than Trump’s was in November 2016. Clinton was ahead of Trump in national polls by about 4 percentage points in the final FiveThirtyEight adjusted polling average. The national polls in the U.S. ended up being off by only 2 percentage points, or equal to the average error in previous presidential campaigns over the past 50 years. State polling was slightly worse, but even in the biggest shocker (Wisconsin), the polling average was off by 6 points. A polling miss of that magnitude in France would still result in an easy win for Macron.
But perhaps the biggest difference between the French campaign and the U.S. race is that there has never been a sign that a plurality of voters could be persuaded to vote for Le Pen in the runoff. Macron’s advantage over Le Pen has been fairly steady over the course of the year. Macron’s current lead, 22 percentage points, is well within the range of his average, 20 to 30 points, since January. In the U.S., Trump closed to within a couple percentage points of Clinton on a number of occasions. That showed that in the right moment he could come close to if not beat Clinton.
When Trump closed the gap on Clinton after the “Comey Letter” late in the campaign, for instance, he was probably winning back a number of voters who had favored him before. Le Pen would likely need to win over voters who have never previously thought of voting for her (and even that might not be enough).