I disagree with your reading. Specifically, it doesn't say that 67,000 people died of the flu, it says that 67,000 people died. The entire report is about all-cause mortality, and so is that sentence. The flu was the reason for a spike in deaths, but it was not the cause of all 67,000 deaths in France that month.

What I believe to be a more accurate translation:

"In addition, the winter flu epidemic that began at the end of 2016 led to an exceptional peak in deaths in January 2017: 67,000 deaths in mainland France this month."