Yes. Reading in poor light will cause eye strain because your pupils will dilate or widen to allow more light in so that you can focus on small objects. And when you read in poor light , you tend to blink less, which will cause eye strain and result in dryness of the eyes. Finally, your eyes are damaged and your eyesight get even worse.
No. Reading in poor light won't damage your eyes. However, it may cause some other problems. When you read in poor light for a long period of time, it will strain your eye muscle and make it ache. So you might get sore eyeballs, headaches, back and neck aches, drooping eyelids, blurred vision, and dryness in your eyes, which won't cause damage to your eyes and they will go away after you stop straining your eye muscle.