Kant's influence cannot be measured by the number of his specific theses which are considered correct today. What Kant discovered was a new concept, a new way of thinking, a new rationalist philosophical paradigm. And this paradigm was more suitable to the modern mind than its rationalist predecessors. In a characteristic methodical manner, Kant took the new paradigm deep and wide, leaving no philosophical stone unturned. With this he shook the philosophical world to the core. And so the philosophy after Kant is tangibly different from the philosophy before Kant.
Kant famously said that David Hume's work woke him up from his slumber. Kant criticized Hume's empiricism on many issues, but he accepted, and further defended, the general thesis that knowledge cannot be had from beyond the bounds of possible sense experience. The combined attacks of Hume's empiricism and Kant's rationalism against the very possibility of transcendent knowledge was very effective. Since Kant and Hume, the possibility of transcendent knowledge is considered hopeless, and is therefore no longer taken seriously in mainstream philosophy. And this is the kind of historical influence that the Object Oriented Philosophers hope to overturn.