Hi Sergio Panagìa,
Social media primarily plays a funnel-broadening role — to help us get our journalism in front of more globally curious people on the platforms where they spend the bulk of their time.
That said, it is also becoming an important drive of subscriptions. Facebook continues to be our largest source of subs. I can’t reveal specific numbers, though.
The challenge for us, and probably for many publishers, is tracking the full user journey. It’s unlikely that someone will immediately subscribe to The Economist after clicking on a Facebook post (or at least not many would do this). We believe that social media is one of several important touch points for prospective subscribers.