Get all employee who directly or indirectly reports to an employee, with hierarchy level no

You could use a recursive CTE:

; with  CTE as 
        (
        select  emp_id
        ,       reports_to
        ,       emp_name
        ,       1 as level
        from    Emp
        where   emp_name = 'Sumanta'
        union all
        select  child.emp_id
        ,       child.reports_to
        ,       child.emp_name
        ,       level + 1
        from    Emp child
        join    CTE parent
        on      child.reports_to = parent.emp_id
        )
select  *
from    CTE

Example at SQL Fiddle.