Here are some thoughts on it from José Valim: https://dashbit.co/blog/why-elixir-best-language-for-ai

LLMs absolutely understand and write good Elixir. I've done complex OTP and distributed work in tandem with Sonnet/Opus and they understand it well and happily keep up. All the Elixir constructs distinct from ruby are well applied: pipes, multiple function clauses, pattern matching, etc.

I can say that anecdotally, CC/Codex are significantly more accurate and faster working with our 250K lines of Elixir than our 25K lines of JS (though not typescript).