By default, columns in table charts are auto-sized. However, should you wish to customize column sizing, you may do so in the chart's settings.
Open your chart for editing and click the Settings button. Switch to the Columns tab, and click +Add New Formatting Rule.
Select your column, then select Percent from the Column Width dropdown and set your desired percentage. Other columns will auto-adjust size accordingly. Any text overflow in your column will be truncated with ellipsis, and the full text is viewable on hover.
To hide a column, set its percentage width to 0.