No. You can edit the header information using the design tab (see below), but axis text size is fixed. In order to change this you'll need to change system font sizes AFAIK.
If you'd like to change the axis text, you'll need to enter the right click menu and select Dashlet Properties. Once that context menu opens, you'll want to select the Axis tab. You'll find the fields to customize the axis text on the upper left corner.