But escape velocity refers to objects with mass, which light is without. Really its more about bending spacetime so much that light among all else gets trapped in a well of it.
Light is subject to escape velocity the same as matter is. A black hole is just as black in a Newtonian universe as an Einsteinian one. Without an understanding of the warping of spacetime he had no idea of the truly one-way nature of a black hole, but he was right about light not being able to make it out. It's an approximation but a pretty good one.
escape velocity does not explicitly refer to an object with mass. One of the earliest observations about gravity is that the acceleration that results is independent of the mass of the falling object. This is why it is called escape velocity instead of escape momentum.