As of @Vicinus@piefed.zip's last Fediverse 'census' a month ago, the Threadiverse (Lemmy+Piefed+Mbin+PyLova) had about 38,800 monthly active users.
Lacking the marketing and development budget of Reddit, the Threadiverse won't be overtaking it any time soon, but aside from the fact that every service needs early adopters to get off the ground, there are plenty of reasons (less spam and promotion, less centralization, less top-down unaccountable moderation) why the smaller communities here can be better than their Reddit counterparts.