NVidia announed at GDC that non-RTX cards will receive support for RTX in a new driver release in April/2019. The models include are:
Pascal:
GTX 1060 6GB
GTX 1070/1070TI
GTX 1080/1080TI
Titan XP/Xp
Volta:
Titan V
Turing:
GTX 1660/1660TI
As for T4, you need to ask at NVidia’s forum, because I think none at Epic will have this specific answer since it is a very specific card for IA.