I have included php_v8js.dll in my regular builds of PHP7 for Windows:
https://www.apachelounge.com/viewtopic.php?t=6359
This is with V8 version 4.7.80.32, as you can see in the phpinfo() dump:
https://phpdev.toolsforresearch.com/php-7.0.4-Win32-VC14-x64.htm
If anyone knows how to compile V8 version 5.x with VC14, I could upgrade as well.