Apart from job postings and Launch HNs, YC-funded startups don't have access to any information or influence that isn't available to anyone else.

We literally give exactly the same information and help to YC-funded startups as we do to non-YC-funded startups who ask for assistance with their Show HNs. That's because giving “extra help” to YC-funded startups is far less valuable (to everyone including the startup themselves [1]) than just making HN interesting to readers and showcasing cool projects, no matter who has built them.

[1] More than almost anything else, what I've learned from moderating HN is that “extra help” to get onto the front page of HN is of barely any help at all. That is, if the post isn't interesting enough to earn significant numbers of upvotes and good comments very quickly, it will disappear off the front page very quickly. Also, any time a story is on the front page that the community doesn’t think belongs there, it feels off and attracts flags and complaints.