"We look forward to meeting with you ..."
You can usually tell if a verb is functioning as a gerund by substituting other nouns to see if the sentence continues to make sense. So ...
"We look forward to it" - sounds okay to me!
So "meeting with you" is functioning as a gerund phrase.
Perhaps, it might help you if you consider the word 'to' to belong to the verbal phrase 'to look forward to' rather than the verb 'to meet'.