There's a utility that helps GitLab users export repository settings from GitLab server. Get the JAR file and follow instructions at GitLab to TSV. Requires Git Integration for JIRA add-on to work.

This utility will create a JIRA Git plugin TSV import file which can be imported via Bulk Change feature of the Git plugin.

Watch the following animated gif on how to import a TSV file generated from this utility:

[GitLab to TSV, how to]