how to find holiday effect on revenue?
It might be not the best approach, but without knowing the data its hard to be precise. 
If you have no ideas where to start, I can suggest trying this things first.


If you want to get the "impact" of the holiday, try to one-hot encode "holiday" variable, and use some simple model that is interpretable. You need to undestand how each holiday-feature impacts the revenue, maybe linear regressiong is a good way to start and move on to more advanced algo`s.
You can try to play with Facebook`s Prophet - its an package for timeseries predictions, wich shows the daily impacts by default. Here is the link: https://research.fb.com/prophet-forecasting-at-scale/ . And link to python package: https://github.com/facebook/prophet


Additional post about Propet and transactios forecasting: https://www.kaggle.com/armamut/predicting-transactions-fb-prophet-tutorial