I have gone through the documentation and it is my understanding that Qualtrics does not have an API that can be used to export the hierarchy associated with a survey.
Please let me know if the only way to export the hierarchy is to manually export the hierarchy as explained in the web page below.
https://www.qualtrics.com/support/employee-experience/creating-ee-project/participants-tab/org-hierarchies/hierarchy-tools/org-hierarchies-export-import-options-ee/