Obviously in Paris more and more people know English since it's a touristic area. But it isn't like Berlin,Amsterdam or Brussels where you can live with very little local language knowledge. Correct french is a pain in the ass to learn, the language is needlessly complicated.
Frankly If I were a "foreigner" (outside the EU) who wants to move to a non English speaking European country, I'd go to Germany, Netherlands, Belgium, Spain, Switzerland, Sweden or Austria. I lived and worked in all these countries without problem and with little knowledge of the local language.
Just don't come here with 0 french and expect to find work, that's not realistic. If you are an "expat" (i.e. you already have a guaranteed job in France), then by all means...