Was the work of syed ahmed shaheed the most important factor in the revival of Islam in the period 1700-1850?

Yes, the work of Syed Ahmad Shaheed Brailvi, Shah Wali Ullah Muhaddis Dhlvi and his sons was the most important factor in the revival of Islam in that period. Anyhow, the services of many scholars,Madrissas and Sufis during that period can't be ignored.