This one is much simpler. Maybe because the lawyers being used are not too good.
Authors claim a lot of stuff, basically a generic shotgun of copyright claims, but all secondary claims get dismissed by the court at pre-trial stage due to bad legal reasoning and failing to detail or prove any actual wrongdoing. And specifically a claim that all outputs from a LLM are derived works of all inputs is dismissed based on already decided case law.
Only the claim of direct copyright infringement of using a text of a book in the training process of a model still stands to avait the actual trial. And there OpenAI is citing a lot of good reasons why that does not constitute distribution at all and why the result of the work is transformative and thus is protected by fair use. Just the fact of accessing some data at some point does not create copyright infringement. The whole lawsuit is very sloppy IMHO, IANAL.