Anything saved to the database will be preserved during your theme, plugin, and WordPress update. Updates usually only effect the code files. Now, if you hack your theme files, or plugin files, or even your WordPress core files, any of those code changes you made would be lost during an update. However, if all your changes were made on a child theme, then you are safe to update the parent theme without risking losing any code in your child theme.

An update deletes code files, and replaces it with new and better code. The code will still pull the same information saved in your database.