For example, Elixir is a more "strict" dynamic language than your usual Python/Ruby/Javascript. Data is immutable. There is no monkey patching. Most state changes happen explicitly via process communication. The macro system is compile-time which means nothing will pull the carpet under your feet at runtime.
Also long-term productivity is about actually maintaining your system in production. And Elixir leverages 3 decades of experience on that, using a runtime designed to build systems that self-heal and are fault-tolerant (I slightly explore this here: http://blog.plataformatec.com.br/2015/06/elixir-in-times-of-...).
I don't want to give a yes or a no answer, I would just like to point out the line is much blurrier than that. It doesn't matter which type system you use, your code is going to have bugs or unexpected situations will arise, specially when we are talking about network. So knowing that your system system can heal itself is quite comforting.
Those are two complementary aspects. It is one of the reasons I would love to see a statically typed language succeed in the Erlang VM.