Not SEO as such as obviously SEO on Etsy relates to writing your listings etc so that the search engine bots index you and hopefully you are placed in a decent place on in searches (on search engines.)
What FB etc can help with is traffic. I am not aware (because I haven't looked) that FB updates are indexed but presumably there is an ability for it to happen. However from your point the benefit of FB is getting friends and followers to look at your new listings, like, comment on and share with others. I am not a FB expert as I am relatively new to it but I can vouch that I do have some traffic from FB and have had a few related sales and that is before I have decided how best to use it for me as well.
You can increase your following by teams such as Etsians of Facebook where you can like each other. Some of it will be 'artifical' liking but don't forget other Etsy sellers are buyers and they all have friends and followers and so on. There are numerous articles on Google about FB marketing and how it can work for you.
http://www.etsy.com/teams/10355/etsians-of-facebook
