Depends on where your team resides. In SF, you could use an average of $135k for all-in costs for each employee. In Toronto, you could probably drop that by 20-30k per person.
But there are so many other factors related to burn beyond headcount that just using a headcount cost + overheard to estimate burn would be pretty inaccurate to reality of calculating a cash-out date.
Happy to talk through the details of your situation in a call.