When you are uploading them you can chose to keep the paper private or make it publicly available. If private, you can chose to release it whenever you want or even not at all.
You can make the abstract public if you want.
I have included one of my papers as an example.
I look forward to seeing your work
Article 150 REVERSAL OF FORTUNES: RIGHT ARM-LEFT ARM ECG LEAD MISPLACEMENT
Please note that ResearchGate is not a publisher and not a journal, you cannot "publish" a paper here. It is a platform for papers published in journals, or to present unpublished texts, data etc. See also "Is ResearchGate a publisher?" in https://help.researchgate.net/hc/en-us/articles/14292596164753. And see this help page ("How to add research") for instructions how to add published or unpublished research to ResearchGate: https://help.researchgate.net/hc/en-us/articles/14293005132305