If you’re prepared to re-write your PHP in JavaScript, then yes, Node.js can replace your Apache.
If you place an Apache or NGINX instance running in reverse-proxy mode between your servers and your clients, you could handle some requests in JavaScript on Node.js and some requests in your Apache-hosted PHP, until you can completely replace all your PHP with JavaScript code. This might be the happy medium: do your WebSockets work in Node.js, more mundane work in Apache + PHP.