The base pay for a game master is $16 an hour, base on Glassdoor report on that, would be ~$2,560/month. (Not sure where you got that number from to be honest.) At $16 an hour, an 8 hour work shift at 5 days a week, a person would get pay $640 for that week. Not counting overtime or weekend work. But if we do count weekend work, it’s just up to $896 a week without overtime.
Seeing as one shift won’t cover a day, (seeing as players can and will do/say things around the clock), we’d need to cover those other others. So that’d jump up to $1,920 for just a week. That’d, also, be just a five day week without overtime. For a 7 day work week, it’d be ~$2,688, a month of that would be ~$10,752. Mind you, this is before taxes and overtime. This is just for one server.
For roughly 241 server in NA, it’d come out to ~$2,591,232 a month. For a year of this, it’d be ~$31,094,784. This is just for the one chat for a given main city. But let say the can view trade, general and I think the city defends on one screen. But that won’t really stop the issue fir other zones and places commonly play in, so they’d also need folks watching the chat and upping the cost as well.