I am considering the option of migrating from TFS to a cloud functional management program and Jira Cloud is an option. The problem is that we have TFS 2017 on premises and there is not much information about whether a safe migration is possible.
Atlassian has a guide on how to do this in Jira Server over inImporting data from TFS or Visual Studio. These steps are effectively the same as importing into Jira Cloud, provided that youfollow the instructions in the Importing data from CSV page for Cloud.
That page itself even notes other alternative and easier ways to migrate this data:
If you are looking for an easier solution
The import through CSV has certain limitations. If the results aren't satisfactory, there are complete third party solutions available which might help you. Please check out the following solutions from Atlassian Marketplace: