Did you follow https://github.com/MeetMe/jira-gerrit-plugin#getting-started ?
It will not auto-close anything. But it is possible to create a workflow action that will submit the change in Gerrit (assuming it has the correct votes) when following a workflow action. There are workflow conditions (i.e., if there are any matching reviews matching the given approval score, such as Code-Review == +2), and workflow functions (i.e., --submit and/or --verified +1) that can be added to any new or existing workflow action.
--submit
--verified +1
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