When adding a table to a layout, the records do not appear in the sort order shown in the table window.
When a table window is sorted, there is no information stored with the table window that describes how the table was sorted. As a result, when you add this table to the layout the sort order can't be re-applied.
Create a report based on the data in the table window and add the report to the layout. When you create a report, you can define the sort order.
For more information, see Desktop Help > Contents > ArcMap > Creating reports.