Yes, even if photons had zero mass, gravitational forces would still bend light. According to the theory of general relativity, gravity is not solely a force acting on mass but is also the curvature of spacetime caused by mass and energy. Light, which consists of photons, travels through this curved spacetime and follows a geodesic, which is the path of shortest distance in curved spacetime.
The bending of light by gravity was famously confirmed during the solar eclipse observation in 1919, when Arthur Eddington's expedition provided experimental evidence for Einstein's general theory of relativity. The light from distant stars passing near the Sun was observed to be bent due to the Sun's gravitational field.
The key point is that the bending of light is caused by the curvature of spacetime, which is influenced by the presence of mass and energy. The mass of photons does not affect their response to gravity because they always travel at the speed of light. Hence, even if photons were massless, they would still be subject to gravitational deflection.