Download and install gnuplot if you do not have it. You can find the windows installer in the "[https://sourceforge.net/projects/gnuplot/files/gnuplot/ gnuplot web site for Files section]" The latest version is 5.0.3.
Make .octaverc in your USERPROFILE directory.
We can find path of USERPROFILE directory by
>> getenv USERPROFILE
make .octaverc in USERPROFILE directory by your favorite text editor and set gnuplot_binary e.g.
gnuplot_binary 'C:\Program Files (x86)\gnuplot\bin\gnuplot.exe'
Please do not forget to quote the path name by single quote (') if name of which has (a) white space(s).
gnuplot ver. 5 supports windows, wxt and qt terminal. On octave, windows terminal is default.
If you want change it to wxt terminal
>> setenv GNUTERM wxt
You can of course describe it
== Octave 4.0.3 on cygwin==