Numbers doesn't provide that control, but does give you some tools that can help center a table both horizontally and vertically on the page.
Here's an example.
Clicking on the small square handle at the lower right corner of the table and holding the mouse button down will display the size of the table. This one is 5.9 inches wide and 2.89 inches high.
The ruler at the top of the window shows a scale telling where the items on the sheet are in relation to the left edge of what will be the print area on page 1. ( 0 ).
Page setup is set to US Letter (8 1/2 inches by 11 inches) and portrait orientation, Pages sets the default left an right margins to 1 inch each, so of the right edge of the print area is at 6.5".

The blue rectangle is a tool I've temporarily added to the sheet using the square shape from the Shapes button.
I resized the width of the square to form an 6 1/2" by (approximately) 1" rectangle, then aligned the left edge of the rectangle with the zero mark on the ruler, and checked to see that the right end was directly under the 6.5 marker.
Using Arrange > move to back, I moved the rectangle behind the table to allow selecting the table and dragging it into position.
A click on a cell activated the table. A second click on the bullseye at the intersection of the row and column reference tabs selected the whole table, allowing me to drag it left or right (and up or down).
As the table approached a horizontally centred position, and it's horizontal aligned with the horizontal centre of the rectangle, a vertical yellow guideline appeared, snapping into place when the table was exactly centred with the rectangle. Releasing the mouse button dropped the table at that position.
The last step(s) were to Lock the table (optional) then select the rectangle and press delete, leaving the table centred horizontally on the page that would be defined when command-P was pressed to open the Print setup mode.
The yellow line in the screen shot, playing the part of the automatic line mentioned in the description, is actually a guideline you can drag out from the vertical ruled and place at the 3.25" point on the ruler, where it becomes a 'permanent' marker of the centre line of th first page. Placing the small square handle at the centre of a selected object (such as a Table) will centre that object left to right on the ''page, as can be seen in the image above.
On the Print Setup page, the table above (with the 'helper rectangle removed) looks like this:

Regards,
Barry