There is no system preference setting for adjusting the cursor blink rate in OS X, as with many hidden settings you can change the blink rate directly using a defaults write command (OS X 10.9 and above).
defaults write -g NSTextInsertionPointBlinkPeriodOn -float 200
defaults write -g NSTextInsertionPointBlinkPeriodOff -float 200
Use milliseconds to adjust the blinking rate (e.g. 1000 = 1 second), change 200 in the value you want to use.
You will need to quit and restart your applications for the changes to take effect,
Reverse to default with the command’s:
defaults delete -g NSTextInsertionPointBlinkPeriodOn
defaults delete -g NSTextInsertionPointBlinkPeriodOff