In very casual speech, you may hear "qu'ont" instead of "qui ont", though. This sounds casual and somewhat childish.
You may even see it written in a quote of what someone said. (Although it is quite possible to correct "qu'ont" back to "qui ont" in quotes)
But in normal speech and in texts, it should stay "qui ont".
Que + il -> Qu'il
Qui + il -> Qui il
However, it is fairly uncommon to find qui il because qui usually comes after the subject...I'm not sure I can explain it very well, I'm afraid - do you already know about subject and object with qui and que?
Actually I do not see how "qui il" can occur as qui and il are both subjects when used in a sentence : "qui il est ?"is improper vs. "qui est-il ?…"
and "Pierre qui il est grand" / "Lui qui il est grand" / " la dame qui elle est belle" / "celui qui il a volé …" do not make any sense contrary to "Pierre qui est grand" / "Lui qui est fort" / "la dame qui est belle" / "celui qui a volé"
All too true !!!…
So much for answering too quickly
However I would rather say "la femme avec laquelle il s'est marié"
But that is only a matter of taste, both are correct … and "je me demande qui il va rencontrer là-bas" has no alternative I can think of
This has to be pretty basic but when I saw the phrase: interprété par Max Rostal qu'accompagne Ian Whyte à la tête du BBC Scottish Orchestra, my brain told me this was wrong, that it should be qui accompagne even though I know we say j'ai au lieu de je ai, etc.
My French training was almost 50 years ago so am I wrong or?
You are right, qui isn't elided when followed with a vowel.
The other possibility that comes to mind is when the usual subject/verb order is reversed after que. If the sentence is intended to mean "that Ian White accompanies," then que would be the intended conjunction. That seems a bit of a stretch in this particular sentence, but perhaps...?
A better example of that would be "the things that Mr. Jones does are...": les choses que fait M. Jones sont...."
From the way the sentence is worded, Max Rostal is the soloist and Ian Whyte is the conductor accompanying the soloist. In that case interprété par Max Rostal qu'accompagne Ian Whyte would be correct since it really means Ian Whyte accompagne Max Rostal, as Kelly B pointed out.
"interprété par Max Rostal qu'accompagne Ian Whyte à la tête du BBC Scottish Orchestra" ..this sentence is correct, it means that Ian Whyte is accompanying Max Rostal. If you were using "qui", you would say "interprété par Max Rostal qui est accompagné par Ian Whyte.