There is always what we call the "chain effect" in that... If people at poor countries got employed and earn bitcoin for themselves ( if they have knowledge about it ) then they are not the liability of their government anymore...
Now, if those poor people use their bitcoin (convert it to fiat) to buy their food and anything, then definitely they are paying tax at that poor country, when those poor people use services at that poor country, definitely they are paying tax...
If half the number of those poor unemployed people earn and pay tax, then definitely there is a great effect in their economy.. There's a lot of big explanation to that, it would take us a day...