Set terminal font size in PhpStorm?

LazyOne already pointed out where you can change this.

Keep in mind that you have to hit the "Save As..." button next to the colour scheme first in order to create a new colour theme - you cannot change anything unless you create a copy.

PHPStorm protip - if you can't find the settings, just use the search field:

Another alternative is hitting CTRL/CMD+Shift+A and searching console:

After setting the font, rebooting is not necessary, just close then open a new terminal as shown here:

Settings (Preferences on Mac) | Editor | Colors & Fonts | Console Font

NOTE: that you cannot edit bundled color scheme -- you will have to make a copy of bundled in order to be able to make changes.