ADB does not see connected Samsung S4
Re-install these official Samsung drivers.


Uninstall current drivers by going into Device Manager. Make sure to check off the delete drivers option if given. 
Reboot. 
Reinstall the given drivers above without connecting the Galaxy S4
Reboot.
Go ahead and connect phone and verify that in device manager Samsung ADB Device or equivalent is shown. 
If it shows an exclamation mark on it or other problem, then in device manager right click on the driver, update, let me choose from a list and choose the correct android adb driver.