There are a couple of ways to go to minimize the stale smoke odour.
Easy and Expensive odour elimination hack:
Rent an ozone generator and let the ozone work within the closed apartment for a while. This is the best non-destructive way. Here's more information Note the safety precautions necessary with ozone.
Hard and Inexpensive odour elimination hack:
Air Ionizers that generate a lot of ozone are great at eliminating smoke smells. Or skip the guessing and buy a small (cheap) ozone generator.
(Warning 1: make sure it's not a fake. See, e.g. photo of eBay item 193723350092 which shows a real and a fake. I have one of each.)
Warning 2: Air Ionizers often generate a lot of ozone, which is hazardous. So ...