In command prompt direct command execution at windows command tamil language is exporting successfully
wkhtmltopdf.exe --encoding UTF-8 http://localhost/pdfexport/phpwkhtmltopdf-master/page.html file/test.pdf
But executing same command via PHP exec($cmd)
tamil strings is not exporting.
To me this sounds like PHP was not configured correctly for UTF8 support.
In pure PHP, without exec(), could you verify this echo "ஆங்கிலம்";
gets printed on screen in a webpage or script of sort?
Do this indepenetly of wkhtmltopdf.