approximately how many jot forms will i be able to submit with the 10 gb plan?

This limit refers to your forms that have a file upload field. The submissions can have file attachments on them and these files will take up the "Upload Space" limit. Please have in mind that this does not reset. It is a fixed limit. If you want to free up your upload space, you can delete submissions that have file uploads on them. However, please note that deleting submission data is irreversible and will permanently remove the data from our servers.

In order to better understand your usage and limits, you can check this guide:

https://eu.jotform.com/help/408-Understanding-Your-Account-Usage-and-Limits

Let us know if we can be of any further assistance.