Welcome to the community.
Simply put, Tableau does not currently support SCIM. However, we'd be very interested in hearing more about how you'd expect to use it in conjunction with Tableau. If you could put together some high-level use cases, and post them here, it would at least get some discussion going.
I'll keep an eye on this thread, and if I come across anything that might be of use, I'll certainly let you know.
Briefly overheard in the corridor "you may potentially create your own SCIM end points with Tableau REST API".
Tableau doesn't provide support for code developed using the REST API, but there's a great reference resource at https://onlinehelp.tableau.com/current/api/rest_api/en-us/REST/rest_api_ref.htm and the Tableau Community Developer Portal may host others with an interest in SCIM.
Tableau Online now supports SCIM! Here's the online documentation describing SCIM support. The OKTA support is in a public beta. Please feel free to reach out to me directly with any feedback on this functionality or if you need help getting it set up. To join the beta officially, email our SCIM pre-release team.