Any sensible employer should treat Erlang and Elixir experience as equivalent. There are important differences, but it would only take 2 weeks for someone experienced with one to be pretty up to speed with the other.

It is, for instance, the opposite situation to C and C++. In that case, they are languages that share syntax but you should code in fundamentally different ways. Erlang and Elixir don't share syntax, but all the important core concepts are the same.

There are a few more substantial differences, like Elixir utiling binaries rather than Erlang's 'strings' that I think are nice improvements, but I was never worried about getting up to speed with Elixir. The tricky bits of working with BEAM are nicely illustrated here:

https://ferd.ca/ten-years-of-erlang.html