If you mod a subreddit you can see stats. On the biggest one I mod (35k subscribers) 2.5% of the traffic comes from Old Reddit, compared to 41% from New Reddit

If you mod a subreddit you can see stats. On the biggest one I mod (35k subscribers) 2.5% of the traffic comes from Old Reddit, compared to 41% from New Reddit and 16% from Mobile Web, and the rest from mobile apps. Unsure why they differentiate Mobile Web from the others, since it's possible to view either Old or New Reddit in mobile browsers. Regardless, Old Reddit is not very popular.