Assuming you mean enabling SSO via SAML from Okta to PeopleSoft applications hosted on premise (e.g. HR/Financials/etc.), then yes, this has been done in the past. It is well documented on the Oracle website which includes an Okta example. The integration requires the SAML configuration to be done on the WebLogic console (I believe v12+). Take a look at the posting on Oracle's blog site. Good luck!