@govind.
Family 1BHK semi furnished will be around 4k-8k in Doha and 2k-5k outside Doha
Food if you cook - 200 QR per month per head
Food if you dont cook - 1k to 1.5k per month per head
Travelling if you live in Doha and dont have a car - 1k QR/ month
Travelling if you live outside Doha and dont have a car - 2k to 3k QR/month assuming your office will be in Doha and you will have to travel everyday
schooling is expensive. take 2k every month.
total would be somewhere around 8k to 12k per month expenses.

When you apply for license then you will spend around 4k to 5k QR and then you will need a car. so plan accordingly. You will not be able to bring your family right away will take atleast 3 months for you to come and setup everything before u can start application for family visit visa.

6k u can stay alive in Qatar alone. But, just stay alive. Not live your life and bring ur family.