It's pronounced as you would say "tay" in RP. Or at least it is in the part of Wales I grew up in (South West).
What Do You Mean By "RP"? Because The Only Think I Know It To Mean Is "Roleplay", Which Doesn't Make Much Sense In This Situation.
Received Pronunciation: https://en.wikipedia.org/wiki/Received_Pronunciation
A particular pronunciation/accent of British English.