How can I back up my Mac Auto Correct & Keyboard shortcuts
For text substitutions, the answer is here (and being OsX we should have guessed it by ourselves): https://support.apple.com/en-us/HT204006

Not sure why you want to export the shortcuts, unless you customized a lot of them... however someone else asked for it: https://www.reddit.com/r/osx/comments/4fx2wo/is_there_a_way_to_saveexport_keyboard_shortcuts/