Gravitational field near event horizon is simply equal to g=GM/R^2=c^2/R=c^4/GM, and near, say our Milky Way core black hole event horizon is about 6x10^8 g, which is way less than gravity on ordinary neutron star(about 10^11 g), so behavior of matter at such fields is well known.

Another remark. Event horizon is relative thing (different for different observers close and far from BH). Therefore, radius of circular photon orbit is different depending where you are. If you are around the event horizon for infinite observer, you actually see infinite radius (straight line).

But anyway, if photon gets lost near BH, its energy is transfered to BH and BH hets bigger and with stronger gravity.