Try this
DECLARE @SQLString nvarchar(500);
DECLARE @ParmDefinition nvarchar(500);
DECLARE @TDATA varchar(30);
declare @QName varchar(50)='TBL_Q6310'
SET @SQLString = N'SELECT @TDATAOUT = Count(*) FROM '+@QName
SET @ParmDefinition = N' @TDATAOUT varchar(30) OUTPUT';
print @SQLString
print @ParmDefinition
EXECUTE sp_executesql @SQLString, @ParmDefinition, @TDATAOUT=@TDATA OUTPUT;
SELECT @TDATA;