All Guest Affiliates are responsible to organize their own funding to bring their sabbatical to IIASA. Many universities have provisions for taking sabbaticals and spending them abroad.
In addition, IIASA has Member Organizations (MOs) in 20 countries, some of which are willing to fund the living costs for a researcher to bring their sabbatical to IIASA. It is recommended that you directly reach out to your MO, to establish which type of support (if any) could be provided.