Although it's interesting to see the stats compared, I think it's a bit of an apple vs orange situation. Steemit seems geared more for content producers. I've mainly just seen articles. While FB is that and lots other thing.
I don't come to Steemit to post a quick meme or check out what my family is up to. I can use Steemit for content I've produced and look at other authors and artitst and support them.
I guess I'm just not convinced that if Steemit does well, that means FB has to be doomed. I see them running parallel if anything.
The thing is Facebook has been trying to "gear more for content producers" for some time now. But they're failing because they don't provide the proper incentives. They want people to post original content and FB rewards them by allowing more people to see that content. The user may be rewarded with more Likes at their page but that's it. Some large news producers on FB have even been offered ad revenue profit sharing, kinda like YouTube and Google ad shares.
It's all very interesting.