I'm no personal injury attorney but I don't think the law with regard to assault has changed much in a long time. It makes sense to me. It isn't nice to put someone in a reasonable fear of imminent harm (def. of assault if I remember correctly). If I walk up to you and put an empty gun to your head and pull the trigger, that is assault. If a woman comes up to me and points her finger toward me and pokes me with it, it is up to a jury to decide if I had a reasonable fear of imminent harm. My guess is the answer is no.
Battery is a little different. It isn't nice to touch people in a harmful or offensive way (I can't remember the definition of battery). She battered him. If she merely touched his arm to get his attention, that's another thing.
As an aside or "sidebar", you can have a battery without an assault. Punch a blind guy in the face or smack someone in the back of the head, etc.
So she's guilty of battery. Criminal case - slap on the wrist or whatever the judge decides based on priors, etc. This is where his actions come in. How egregious was her action based on the circumstances?
Civil case - look at damages, which would be next to nothing. The reason the suit is being brought is because he's angry and, most importantly, because she is rich. He and his attorney are gambling that she would rather give him $5k to go away than to pay an attorney $10k to go to court. No worries about the case being frivolous because she actually did poke him. Oh, she's famous too. He is in a position to generate a lot of bad press for her, making her desire to settle even greater.