As long as they have enough savings set aside for the shutdown, which granted, many do not, they'll all be getting pay retroactively for time they were not even at work. Many creditors, insurance companies, etc have announced that bills normally due and payable will be deferred for government employees during the shutdown.
For those that DO have enough money saved to get by, the shutdown in reality is akin to a gloriously unscheduled and extended PAID vacation.
Honestly, if I was a federal government employee able to weather the financial aspect of a shutdown, I would hope a shutdown would last many months knowing I would actually get paid for that time away from work. No question, I would actually be gleeful and I don't mean that facetiously. Extra time off from work to do whatever I want, get paid for it retroactively and not have the time off affect my regular vacation days?