Just because more words exist, does not mean the authors make use of these words. I think the author would agree that English has more words - he cites the dictionary sizes skewing heavily in favor of English.

With that said, I am also surprised. I would like to see a similar analysis using more modern works, as well as a discussion around how texts are selected. It seems like the selection of authors and their novels will significantly impact the results.

FWIW - Both English and French stem from the same original language (Proto-Indo-European). You are correct that English is a Germanic language (this does not mean it stems from German), and the French is a Romance language - with Romance being used in the sense of "came from Rome," not "sounds sexy." If you are interested in more details here, I highly recommend "The History of English" podcast: http://historyofenglishpodcast.com/ I'm still working my way through it, but it does a great job explaining the history of the English language, how it evolved, how it relates to other languages, etc.

English contains words from many other languages. It is not just Latin words, but many more recent languages (such as French) as well.