21K PLN is a lof of money
So is 1.85 lakh. With cost of living and cost of schooling for the child taken into account, he may be better off staying in India.
s it worth moving to Krakow
Probably not. Your chances for advancement are probably higher using India as a base than using Poland as a "foot in the door" to the richer countries of the EU. Living in Poland will probably not increase your chances of finding work in a richer country that is more receptive to Indians. As for staying in Poland long term, very few Indians do. By far the overwhelming majority either move west, legally or illegally, or return home within a few years at most.
Also, Poland has become a less attractive destination for Indians, and Indians have become less attractive employees to Polish companies over the last five years. This forum hardly ever gets questions like yours anymore, whereas five, ten years ago it got several a week. The golden age for Indian workers in Poland is long past.