This isn't something that's quantifiable through just 2016 streaming/album #s and ability to sell out stadiums. There are factors that aren't tangible you have to consider. Beyoncé is a generation defining artist. She can remain on the pantheon of musicians until she's an old lady. Her level of influence to this generation is comparable to some of the greatest and most accomplished musicians ever and their generations. She's looked at the same way people looked at Whitney Houston, Mariah, Tina turner, etc. She is a god to damn near every woman 50 and under. On some Oprah ****.
Drake is a rapper. A genre that lives within its youth. It's not even possible for him to have that level of influence over a longer period of time than someone like Beyoncé.
If you want to tell me that Drake can sell more first week streams or whatever the hell criteria it is they use to track sales these days...fine. But to say that Drake is bigger than Beyoncé is completely asinine.