Yes, 受けた modifies 人
The comma is often used in this way for both style and clarity. If there was no comma, as in:
東日本大震災で被害を受けた目に障害がある人に「語り 部」になってもらい。。。
the sentence would sound a bit disorganized and clunky. A comma makes it sound much better. It also reflects how it is actually spoken in Japanese, with a slight pause between 受けた and 目
Also, without a comma, in some sentences (but not this one), there could be ambiguity over whether 受けた modifies 目, or whether it modifies 人, for example, and thus the comma helps show that it actually modifies 人. In this case it's pretty obvious that an eye cannot be affected by an earthquake, but in many contexts it is not so clear.