I didn't take any overhead in account, just checked that the site itself was a bit under 2kB worth of data. 1 gigabit / 2 kilobytes = 62500, so in order to consume 1Gbps you'll need about that 62k visitors every second. Handshake is few hundred bits and other overhead is pretty neglible, but those are still not zero so I just rounded it down for a rough ballpark number.