Early Elite absolutely took some plot structure and other aspects from Gossip Girl. First of all, the class conflict between the poorer students and the ultra-rich, the scheming queen bee; heck, Lu's looks early on were clearly inspired directly by Blair Wardoff's look. Also the constant parties, similar in structure to the "final party" in (nearly) every episode of the original Gossip Girl.
But the season structure is definitely ripped straight off of How to Get Away With Murder: The season starting with something horrible happening, then most of the season telling the lead-up to the horrible thing, with the occasional brief fast-forwards, all inspired by HtGAWM.