are readers actually willing to donate to people (assuming that is from their own holdings)

I actually love consuming content on the internet (mostly youtube) if the steem/hive blockchain was the best way to watch/read things I normally watch, I would be happy to tip some of my personal holdings for it in case it was convenient like the upvote button now. Unfortunately, content on steem/hive is 99.9% pure garbage and there is little to no way to filter it. Ths system is just designed to make quick shitposts to get the rewards. The entire platform is like a library where nearly all of the books are about the library itself because that is what everyone here is at least a bit into and will get the upvotes. If you try to make a real community around a specific subject you mostly just get people pretending using it to get some earnings.

how much add revenue could really be made based on the blog posts

There is a reason why the view counter on posts was removed a long time ago. Nobody is reading posts or watching videos on Steem/hive/Dtube/3speak. Most 3speak videos have 10-30 views at best and many of those have 10$-60$ payouts which doesn't make any sense at all.

Without actual revenue or real donations as the dominant factor behind the post-earnings, it's all just a fugazi and a Ponzi which is bound to collapse at some point.

The blockchain itself does work really well though and the resource credit system has good potential to give the token value. I did like the old system where it was actually possible to build your own account, blog and earnings. The non-linear reward curve killed that as the only way to get decent upvotes now is to pray to the curation gods or bend your content to their ways.

Publish0x has a way better blogging earnings model. The reward pool is donated by projects who get some exposure in return. All members get 6 daily upvotes who give from that reward pool. 10 minutes need to be between upvotes and 24 hours between upvoting the same person. Payouts are realistic (if you get 1$-5$ you are able to get on trending) but you need a lot of views 3000+ for those. The average content is way better on publish0x and there are real readers. It is highly centralized and I'm not sure if it will ever be able to scale though.

My enthusiasm for Steem/hive is quite low at the moment. I still enjoy having a personal blog and I love Splinterlands but that's about it. I can't say I have high hopes for this to really work in the current format.