Want to upgrade the average internet plan from 100 Mbps to 1 Gbps for my broadband users.

What should I do to start providing 1 Gbps internet speed to home users? Currently, I have approx 500 customers and I am using 4 EPON OLTs which only have 1 Gbps downstream speed on the PON port so they max out at 1 Gbps. Currently, the average plan per user is 100Mbps. So I don't think these OLTs are suitable for providing 1 Gbps speed to the home users. Currently, I am using xPON ONTs at the customer end which work both on EPON and GPON OLTs. Can someone help me?