There's no direct way.
If you don't mind using keyboard instead of mouse then
text zooming in GNOME Terminal should work just fine with the usual
Ctrl+
+,
Ctrl+
- and
Ctrl+
0.
There's a
tool that allows zooming with
Alt+
mousewheel, but you have to compile it from source.
For other options, see e.g. the
Debian Wiki.
Caveat. Some of the options described there may be not applicable as is (or at all) to CentOS 7.
At least, the GNOME Accessibility/Universal Access feature Zoom should always work. But it's also best
controlled by its keyboard shortcuts.
