When is the exact date for EOL of Ubuntu 14.04 LTS?

The EOL of Ubuntu 14.04 is on the 17th of April 2019.

To obtain the EOL date of any Ubuntu distro you can use the following command

$ ubuntu-distro-info --all -yeol -f 
Ubuntu 14.04 LTS "Trusty Tahr" 29

It will print the days till support ends. Here 29 days.

To install the command use

$ sudo apt install distro-info

To get the date, use e.g. the date command

$ date +"%Y-%m-%d" --date '+29 day'   
2019-04-17

You can automate this with sed, e.g. to get a list of currently supported releases with their EOL date:

$ ubuntu-distro-info --supported -yeol -f | sed "s/.* \([0-9]*\)/echo -n '           &\r';date -d+\1day +%F/e"
2019-04-17 Ubuntu 14.04 LTS "Trusty Tahr" 28
2021-04-21 Ubuntu 16.04 LTS "Xenial Xerus" 763
2023-04-26 Ubuntu 18.04 LTS "Bionic Beaver" 1498
2019-07-18 Ubuntu 18.10 "Cosmic Cuttlefish" 120
2020-01-18 Ubuntu 19.04 "Disco Dingo" 304

According to Ubuntu Version History - Wikipedia

Normal LTS support is set to continue until 25 April 2019,[219] after which extended security maintenance will be available to Ubuntu Advantage customers and as a separate commercial purchase, as was the case previously with 12.04.[220]

Considering the above statement normal LTS updates are expected to be received till 25 April '19.