start struck. To be struck by something is to be hit by it. You can also be struck by an idea. When you are star struck it means you have big eyes and an open face as you stare at a celebrity in the near vicinity. "oooh, I can't believe they said hi to me!!" To capitalize off something means to take advantage of the opportunity. In business, if there is an opportunity to make money, perhaps a new venture, you can capitalize on it by taking advantage of the opportunity and extending your business. Kris wanted something from Jen (to introduce her to Rob), and when the opportunity presented itself she capitalized on it, or took the opportunity.

Star truck was typed incorrectly, what they meant to say was "star struck" meaning fascinated, impressed or "in awe of". The sentence "Kris couldn’t wait to try and capitalize off from the Hunger Games actress" means that because J-Law is so famous and well liked from the Hunger Games movies, Kris is trying to gain media coverage and fame by being around her. Congratulations on having the English skills to read paragraphs as complexly worded as this one.

I think "star truck" is a typo and should be "star-struck." As for "capitalize off," I could be wrong, but I believe it means "to take advantage from the Hunger Games actress." I never actually heard of that expression though, so I'll let to the people that know to chime in ^^