Simula I was a huge influence on Alan, as was Sketchpad (a parallel invention of object oriented programming). But Simula was a hybrid language like the later C++, so in the issue about message passing syntax Smalltalk had a certain impact.

Simula-67 introduced inheritance, which Smalltalk-72 and -74 didn't have. Many people see it as a key OOP feature, which Smalltalk-76 added.

Kristen Nygaard, who with Ole-Johan Dahl had created Simula, was one of the creators of the very pure Beta programming language.

https://en.wikipedia.org/wiki/BETA_(programming_language)

This took the message passing syntax in a very different direction:

    message -> receiver