Get Value
string strEmployeeID = ((Label)(GridView1.Rows[0].Cells[3].Controls[1])).Text
You can assign any value to that control as same way get from that control.
Set Value
string strEmployeeID = "EMP001";
((Label)(GridView1.Rows[0].Cells[3].Controls[1])).Text = strEmployeeID
please change the code based on your requirement.