"Unfortunately the Turkish police took his passport and now he cannot leave and also not pay his bill"
Page 1 of my Canadian passport says "This passport is the property of the Government of Canada". Normally, no one has any grounds to keep it from the bearer of the passport and to demand money for its return.
If the police took his passport for longer than it takes to record his identity and to verify that he is legally allowed to be in Turkey, and they won't give it back, it usually would mean that he was arrested (which usually happens when the police believe they have enough evidence that the arrested person might have committed a crime). Often, when someone is arrested, all of their possessions are removed and documented in writing (including the exact number of coins in their wallet, so that the arrested person can't accuse the police of stealing, or would at least have a harder time proving it). You did say:
"He was even detained for five days"
It would not be unusual for the police to keep the passport during those five days, along with everything else in the arrested person's pockets, including their phone and any other communication device. For the arrested person to call you, they would normally need to use the police station's phone, and normally you would only be able to call a local number (which could include the Canadian embassy in Turkey, but not a friend outside the country like you). If he has told you all of this, it most likely means he's no longer detained, which means he would normally get all of his possessions back including the passport, except in one possible circumstance: he surrendered the passport himself, as part of a bail condition ("bail" is when an arrested person can leave the place where they're being held in custody, under some conditions, and surrendering a passport is a common one when the arrested person is not in their own country, because not having a passport reduces the possibility of the arrested person being a "flight risk"). If this is the case (i.e. he is calling you while on bail, with a passport surrendered to the police), then it would seem they want to keep him in Turkey while they continue their criminal investigation. You said:
"according to him he needs to fly home (Canada) to sort everything out"
That will not be happening if he is on bail with his passport surrendered to the Turkish police. You also said:
"he cannot leave and also not pay his bill"
What precisely does he have to pay? If it's a hotel bill, then it normally would be a matter of civil law and not a matter of criminal law, so the hotel would have to sue him for a court to order him to settle his civil debt. It would be extremely surprising to me if he is being arrested by police in Turkey just for not settling a debt. Police detain people for criminal matters, not civil matters, and if it's a criminal matter, you need to carefully consider how far you want to help this friend. I can understand if he needs money to pay for bail, but if he's talking to you he's likely already on bail. You said:
"I find it strange that he cannot arrange his bank affairs online. Do you know if this is the case with the Canadian banks that you have to be there in person."
Most Canadian banks have some sort of online banking, and international credit cards do work in most places in Turkey. However I know that at least TD Bank, which is the largest bank in Canada has recently made it extremely difficult to use online banking from abroad due to requiring 2-factor authentication when traveling, which either requires having the phone on which the bank's app was registered, or requires being able to answer a text message or phone call to the account holder's phone number on TD Bank's file (which is not always easy when traveling internationally). This is actually the reason I switched to a different bank, so indeed with Canada's largest bank it has recently become hard to do online banking while traveling internationally if without the account holder's Canadian phone, but travelers on business trips usually have the means to pay for any expected costs during their trip (and typically have to convince immigration staff at the airport, that they have enough money to sustain themselves during the trip, in order to be allowed into the country).
In conclusion: The story is suspicious and as the other answer suggests, I wouldn't send them money if I were you.
A minor additional note: You said,
"His bank pass was stolen..."
As a Canadian, I've never heard the term "bank pass". In the 90s something called a "passbook" was popular, but it wouldn't be any use in Turkey. If it was him that used the phrase "bank pass", I would find his story even more suspicious.