The short answer is NO. I'm not sure where this rumour was started or how it came about, but if I had to guess I would assume somebody who dislikes PHP (there are lots of devs that dislike PHP!) said something along the lines of, "PHP is a bad language" and after several iterations, people started saying it was "dying".
It was just yesterday I was saying "WordPress powers ~27% of all websites.". Turns out I was wrong.. it's now 30%! Don't believe me? Go to WordPress.com and see for yourself — they proudly display this fact!
Many developers think PHP is a terrible programming language. In fact, it's not bad at all, it's actually quite modern. PHP7 is as as fast as Python 3, and despite the syntax being wildly different between the two languages, PHP is drastically more common for a typical website.
WordPress runs on PHP meaning that at least 30% of all websites are using PHP. That doesn't include companies like Facebook that started with PHP (they hacked up PHP to make it faster in a language they call "Hack"; which is now very similar to PHP7 I find). Yahoo! (remember them?!) started with PHP. Thousands of startups are using PHP because it doesn't care if there's an error.. it just keeps going! Plus there's Drupal and Joomla websites out there. And what about almost all the forums out there? Most of them are PHP, as well!
But the main reason you should learn PHP is to satisfy demand. This gets into the most basic form of economics: if there's demand for something, you should be prepared to fulfill that demand.
One in three websites are running WordPress, and many more are using other CMS's or have been coded from scratch using PHP. That means there's a high usage of PHP, and a high demand for good PHP developers.
You don't have to like it, but you need to acknowledge the facts
The honest truth is PHP is getting more and more popular. People have started entire companies around making plugins for WordPress, or just creating themes! I personally have started a couple startups that used PHP because it was the right language for the job.
You don't have to like it, but you need to acknowledge the facts. PHP is growing, it's not dying. If you want to start freelancing, or get a job — learn PHP! It's not hard to learn and it'll ensure you will be able to get a job (remote or local) in almost every city you're in.
Today I'm a full stack LAMPP (PHP and Python) developer that enjoys teaching web development and working with startups.