worth noting that this is the theoretical maximum capacity if the DWDM chassis at all ends were fully populated. Likely using 100, 200 and 400Gbps coherent (QPSK, 8PSK and 16QAM modulated) optics in a 50 GHz ITU DWDM grid. It's not as if it's going to have that capacity at the beginning. And no single circuit will have that capacity.

The math probably looks something like this:

Per 2 fiber pair, 80 channels x 200 Gbps per coherent wavelength = 16000 Gbps