In Debord's explicit engagement with surrealism, he admits its influence. Detournement, for example, draws equally from Asger Jorn's technique of "modification" and Surrealist collage.

Furthermore, as a Marxist, he'd have to admit the dialectical (material) influence of surrealism and its offshots, including his.

Also - Situationist tactics are just as prone to recuperation as Surrealism. Anti-advertising, street art, etc. are totally integrated.

To add further nuance, Surrealism continued after Breton, et al. Surrealist groups still exist and were acting in parallel to the Situationists in the late '60s. For example, the Chicago group emerged from the Industrial Workers of the World/SDS, staged interventions (a la situations) and were among the first to distribute Situationist literature through their bookshop.