No, the gateway doesn’t currently support such granular permissions. The ‘Terminate’ button is visible if the client has access to the config section of the gateway.
You could put a feature request on ideas.inductiveautomation.com, though.
If you’ve got at least one client open for supervisors, you could use system.util.sendMessage() and system.util.exit() to implement basically the same thing - just have a message handler on each client waiting for a terminate message, and run system.util.exit(). system.util.getSessionInfo() would give you the session ID(s) to terminate.
Or, if you dig through this forum, you could find access to the (unsupported and undocumented) internal classes used for the gateway, and use one of those to send a remote-terminate push message to the client; that’s as much of a hint as I’ll give.