There is an enormous volume of literature on this. The following may provide a useful introduction:
Robert Francis Cook, ‘Crusade propaganda in the epic cycles of the crusade’, in Journeys Toward God: Pilgrimage and Crusade, ed. Barbara N. Sargent-Baur (Kalamazoo: Medieval Institute Publications, 1992), pp. 157–175;
Margaret A. Jubb, The legend of Saladin in Western literature and historiography (Lewiston and Lampeter: Edwin Mellen Press, 2000);
David A. Trotter, Medieval French literature and the crusades (1100–1300) (Geneva: Librairie Droz, 1988).