Hello,
I am not sure what the pay is like in other countries, but in the US you can survive comfortably. I live in Austin, TX and I taught ESL for 8 years at a public middle school. You get paid the same salary that any other teacher in Texas gets paid. I believe most schools in Texas, at least in the Austin area, start first year teachers at $45,000. The other metropolitan areas are the same or more. You get summers off where you can tutor and make more money if need be. You won't get rich, but you won't be too poor
If you get a Master’s you can make a little more. I currently work as an adjunct professor teaching Spanish and ESL for a few different colleges in Austin and online. Full time I believe the community colleges start at $55,000. If you teach adjunct, like I do, you make $900 a credit hour. I have a family of 6 and we live on my salary. It can be done. You won't get rich, but if you do some tutoring in the summer you can make it happen. It is a very rewarding job. I hope this helps.