There is no common XML format for online surveys. Therefore, copying questionnaires from one tool to another is not possible. Another reason is that a lot of details (such as filters) work completely different on different survey tools.
What you can easily do is to copy survey projects between different SoSci Survey servers.
And here are some tips how to copy&paste a questionnaire from a Word document or from another tool to SoSci Survey with least possible effort: Entering Questionnaires Efficiently
We also have considered import options for other survey software. However, whenever we started and asked for details, the responsible persons were already done wiht the workaround.