The GoF patterns have nothing to do with static types. The GoF patterns were created based on work done primarily in Smalltalk, and to a lesser degree C++. Smalltalk is dynamically typed. Indeed, many of the patterns were about how to effectively make decisions using blocks (AKA functions) without static types or isMemberOf:/isKindOf: calls.
Smalltalk was also one of the big influences for Ruby, which in turn influenced Elixir.
