Page views are not related with the Theme and lot of other factors come into the picture when it comes with drop in page views. If you are getting the view predominately from Search engines and/or social media channels then one of the main cause of drop in page views might be changes in algorithms. I suggest you to do following:
Inspect Google analytics as that will give you more information on what might be the reason.
Setup Google webmaster tools as it will give you deep insight on the status of website indexing and inputs that you can take into consideration to optimize visibility of the websites.
I also suggest you to take a look at following resources to get more understanding and some potential solutions: