This doesn't prove where Sylvanus Stokes was born, but it does prove he was living in James City Co prior to moving to Surry Co. This comes from a grant at the LVA search webpage. He was "of James City Co" in 1717, but later of Surry Co.
Stokes, Silvanus of James City Co. grantee.
Land grant 24 January 1717.
Location: Surry County.
Description: 200 acres on the north side of the Raccoon Swamp beginning at a pine by the side of the said swamp a little below the mouth of the Double branch thence north 119 pole to a red oak then east 206 pole to a pine then south 18 degrees east 121 pole to a white oak then south west 119 pole to a gum by the side of the racoon swamp aforesaid and up the various courses of the run of the said swamp to the begining
Source: Land Office Patents No. 10, 1710-1719, p. 362 (Reel 10).