Gabriel has been chairman of the Atlantic Bridge and member of the Trilateral Commission as well as the European Council on Foreign Relations. He has also been a member of the Board of Trustees of the International Crisis Group since May 2018 and since March 2019 the advisory board of Deloitte. In the summer semester of 2018, he was a lecturer at the Rheinische Friedrich-Wilhelms-Universität Bonn and for three weeks in the fall of 2018 a visiting lecturer at Harvard University. Since November 2019, he has been working at Eurasia Group as a political consultant.