Ah he would be ya
Sarcastic agreement that means the exact opposite: not a hope.
He says he's givin' up de drink for Lent." "Ah he would be, ya.

Shall I translate it into posh English for you, horsebox?
Greetings, dear reader. Here it is in posh English.
"He claims he shall forswear alcohol for Lent." "Oh, assuredly he shall. And I am the Archbishop of Canterbury."
Questions
What does ah he would be ya mean in Ireland?
Sarcastic agreement that means the exact opposite: not a hope.
How do you use ah he would be ya in a sentence?
“He says he's givin' up de drink for Lent." "Ah he would be, ya.”
Updated
On the list: Irish slang phrases