Q:

How to interpret 喜んでもらえて私も嬉しいです

In reply to my thank-you-message I received the following: 

喜んでもらえて私も嬉しいです。 

Can it be interpreted as "I am glad that you enjoyed it"? 

A:

Yes.  Exactly.  ^_^ There are other subtle ways someone might choose to translate this, but your interpretation is spot on.