Unquestionably Golang if those are the two options. It’ll give you a much more applicable base to work with if you are still earlier in your career and is much more applicable to a lot of things.

Elixir is niche, the syntax doesn’t share a lot of patterns with other languages, and no one is hiring for it. Also few people know it.

I want to caveat my answer with that I personally really like elixir, and would prefer to work with it myself over golang for some types of problems. Actor patterns are really cool.