It's true, though, and in fact 30% is a conservative estimate. The percentage of English words that come from French varies from 29% to 45% depending on whether you count derivatives of those words.
What overview? That page repeats a bunch of claims on the basis of nothing, with a big banner at the top of the page warning you that none of the content is supported by any evidence.
The only citation on that page is a dead link to a Canadian university's "about our French program" page, which, while it does claim that 45% of all English words "come from French words" (again, on the basis of nothing), nevertheless manages to contradict the Wikipedia page that cites it by estimating the number at 50,000 rather than Wikipedia's reported 80,000.
A very non-exhaustive overview of this is at https://en.wikipedia.org/wiki/List_of_English_words_of_Frenc...