Both PHP and Node.js run server-side, and both are viable choices for building websites. They suit different use cases, and often it makes sense to use both of them together on one site.
This me ans that there are plenty of projects written in PHP, and plenty of PHP developers.
Though both Node.js and PHP are both server side scripting languages, they are bound to have various similarities but there exists various dis-similarities as well between the two scripting languages.
The major reason for this is that they are new and their code design is in such a way that they are inherently resistant to such attacks.