Hello Kevin,
Great question. WordPress updates themes, by deleting the existing theme and replacing it with the new one. So if you make any changes directly to the theme’s files, those would be lost in an update.
Your actual content — pages, posts, podcasts, widgets and so on will be fine in the update. They are all stored in the database instead of the theme files.
If you do need to make changes to the theme files, the best way to do that is with a child theme. There’s a post at https://support.organizedthemes.com/child-themes/ that has some resources on them if you’d like to go that route.
The idea with a child theme is to have your theme modifications kept there. That way you can update the original (parent) theme without losing your changes. Also since you only have modifications in the child, you can get any new functionality or fixes in the parent with the update.
Let me know if I can help.
Thanks,
Bill