People say this all the time, but I've never seen any data proving it's true. Should be rather easy too, I'm at a big company and different teams use different languages. The strictly typed languages do to have fewer defects, and those teams don't ship features any faster than the teams using loosely typed languages.

What I've experienced is that other factors make the biggest difference. Teams that write good tests, have good testing environments, good code review processes, good automation, etc tend to have fewer defects and higher velocity. Choice of programming language makes little to no difference.