How to say: He must have been drunk

[Tycholiz]

Is it correct if I say "ha de haya estado borracho"?

I want to incorporate the formula of haber + de + infinitive.

Thanks!

[ROBINDESBOIS]

Debe de haber estado borracho or better
Debía estar borracho

[AngelicaDeAlquezar]

I want to incorporate the formula of haber + de + infinitive.

You can certainly use such formula, but watch out, "haya" is not an infinitive. :)