For any tag/topic that you want to know more details on - you can go to the tag page:

https://medium.com/tag/<tag_name>

e.g. for technology

https://medium.com/tag/technology

which shows you both the number of followers and the number of stories.

As a bit of a plug for my chrome extension - you could also install it :)

https://chrome.google.com/webstore/detail/medium-topic-insights/ckjnkjieanagpgiaocajoikjaplmjigo