I have a very simple survey with about 8 records in it. When I go to export the data from the data tab, it never finishes exporting. I can see from ArcGIS Online that it starts to create the geodatabase, but never finishes. The "Exporting" tab just keeps spinning per the attached image.
Are you trying to export from the survey123 website data tab, or the data tab in AGO? Also, what format have you tried, i see you mention geodatabase, does exporting to Excel or other formats work?
Do you have image questions or other attachments in the feature layer, and what other types or questions? Are you using repeats (related tables) and if so how many records are in those related tables?