Shalom. According to tradition Elijah will come to "pave the way" and announce the Mashiach's arrival. He is intrinsically connected to the final redemption and salvation of the Jewish People from all enemies and problematic circumstances in this world.
Since Pesachand according to our Sages the future redemption will occur in the month of Pesach which is Nisanwe symbolically invite Elijah to our celebration of our past redemption by opening the door for him and setting a special cup of "wine of redemption" for him at the Seder, as we read in the Hagaddah. With great hope and prayer for the future redemption, may it be very soon.
I hope this clear and helpful and wish you an enjoyable, kosher and inspiring Pesach. I am based in Jerusalem and not NY, and unfortunately cannot attend the Gateways events there with the wonderful staff and guests, but I cannot complain about being in Jerusalem for Pesach!