I'm not sure what Gantt Chart you're trying to embed. Is it some provided by a plugin in JIRA? Which one?
Either way, Confluence has a Gantt macro as you can see here. Though it's not exactly what you asked for, it may be useful.
Jaime Kirch da Silveira
Atlassian Cloud Support
Hi team, I’m Avinoam, a product manager on Confluence Cloud, and today I’m really excited to let the Community know that all customers can now try out the new editing experience and see some of the ...
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