Here are some realistic ways to deal with a knife attack

First of all, if you can run away, running is the best option.
If you cannot run away, you must create a situation where you confront the attacker using nearby objects.

The most recommended object is a chair.
If you hold a chair as shown in the image, you can both defend and attack.
Even experts realistically recommend a chair as the best tool.
If there are multiple people, several individuals can hold chairs to defend while simultaneously subduing the attacker.
Also, if there is a long stick nearby, you can use it to defend and counterattack.
If you have nothing at all, picking up something like a bag or a box to protect your upper body while counterattacking with your feet can buy you some time.
In any case, if you can run away, running is the best option.
Those methods are truly for when it is a last resort.