Well, in the latest vote McCarthy picked up 13 votes from his previous best of 201 (on Monday).  Which might seem impressive until you consider that this is essentially where he had expected to be on the first day of voting.  He's basically picked up the folks that he had not expected to vote against him in the first place, but made no inroads with the core "never Kevins."  And I don't see what his path forward is from here. There doesn't seem much left in the way of concessions he could make, aside from ridiculous things like offering committee chairs, something the moderate supporters would not tolerate.  His strategy now seems to be simply to exert pressure on the remaining holdouts.  But if he thinks people like Gaetz and Boebert are going to be bothered by having the spotlight of public pressure shone on them, he really has a fundamental misunderstanding of what motivates them.

Some moderate Democrats have expressed a willingness to negotiate, but from what I read McCarthy's camp has shown no interest in engaging with them so far.  So there's no opportunity there for Democrats to be missing.  McCarthy has used threats to work with Democrats but the hardliners know those are (at this point) idle threats, so they are not providing him with any leverage.  

They would not need to vote for him.  A handful of Democrats voting "present" instead of Jeffries would lower McCarthy's threshhold for victory and remove his need to attract any remaining Republican holdouts.

As to the notion that there is zero benefit for Democrats in negotiating... there's going to be a Republican speaker one way or another, and it doesn't much matter who it is in terms of how it will affect the political situation for Democrats.  They can't prevent that.  But something is better than nothing, and extracting some concessions in terms of committee assignments, subpoena power, or even an agreement on the debt ceiling would be better than nothing.  But like I said above, that would only be possible if McCarthy was willing to negotiate with them, which at this point he apparently is not.

Which is the exact point that I made? McCarthy isn't going to make those sort of those concessions, so there's zero benefit in the Democrats offering to help him. Any overtures need to come from McCarthy's camp.

Agreed.  But as this drags out, there may be more interest.  Instead of just publicly expressing a willingness to negotiate, it would be smart for Dems to reach out to McCarthy with specific requests.  And maybe this is already happening behind the scenes.

"But something is better than nothing, and extracting some concessions in terms of committee assignments, subpoena power, or even an agreement on the debt ceiling would be better than nothing."

Precisely my point.  Subpoena power would be a tough pill for McCarthy to swallow, but I'm sure they could get some concessions on committees and the debt ceiling.  Maybe I'm not being cynical enough, but I think the opportunity exists, right up until the point when the far right caves...which I still believe they will.

The few remaining holdouts claim they are trying to change the way things work in DC.  If that is true, then they must also realize at some point that "something is better than nothing" and get in line.

The House of Representatives numbers 435, every one of them voted in to do the job of representing the US public in running government. A handful of people, six at present, are blocking this. These six out of 435 do not democratically represent what the public wants. To kowtow to them is to give them vastly disproportionate power with regard to everyone else in the House.