Try the following:

octave:6> more on
octave:7> y = 1:1e7

and hit Ctrl+C somewhere when it is displaying:

 Columns 36 through 42:
-- less -- (f)orward, (b)ack, (q)uit

Octave is still in the pager.  The pager's "follow output" mode needs a Ctrl+C to exit, but Octave is not passing that escape sequence to the pager.  When in pager, type Shft+F, which means to keep moving (pressing) f indefinitely:

[snip]
 Columns 1259567 through 1259573:

    1259567    1259568    1259569    1259570    1259571    1259572    1259573

 Columns 1259574 through 1259580:

    1259574    1259575    1259576    1259577
Waiting for data... (interrupt to abort)

Cntrl-C doesn't work at this point.  (If there is a key sequence for abort, I don't know it.)  So, at this point octave is hung and only killing the process will exit.

Repeat the above sequence without pressing Ctrl+C (use y=1:1e6 if you like), and Ctrl+C still works in the pager after having pressed Shft+F.

Maybe leaving the pager altogether when pressing Ctrl+C during output is the way to go.