If you are rooted, try and replace the emoji font file using the following process:
1. Download the attached "notocoloremoji.zip" and extract the "notocoloremoji.ttf" (this font comes from stock Kit Kat)
2. Using rootbrowser (or similar) replace the "notocoloremoji.ttf" file in system/fonts with the extracted version downloaded in step 1. If you have a notocoloremoji file in system/fonts, you may want to back it up by renaming the file to notocoloremoji-bak or similar.
3. Again, using rootbrowser, change the permissions to 644 (Read for owner, group, and others, but write for only owner)
4. Reboot your device.
If you are still not seeing emoji after replacing that file, check the fallback_fonts.xml file in system/etc to confirm that notocoloremoji.ttf is referenced.