We tracked pipeline and revenue influenced for case studies/content at my previous gig. We had to work with the marketing ops team to implement it, though.
It will be a little different for every company in my experience, but the gist of it was that:
We'd have individual Salesforce campaigns for each content asset (e.g. case study, ebook)
MOps would set up a tracking code for each asset in Marketo. We embedded the case studies as iFrames, so they were ungated, but still trackable
When a prospect/customer viewed the case study, it would append that engagement to the corresponding Campaign, as well as the current open opp/account the contact was tied to in Salesforce
We would run campaign reports in Salesforce to track pipe + revenue influenced
I'm afraid I can't get much more into the nitty gritty on how to do this tactically, as this was set up by the MOps team at my last company, but it was the best method I've found to truly track pipe + rev influence against customer content
