How to substitute canned Apricots with fresh when cooking

If the apricots are just a topping or mix-in, you might actually like it better with fresh than with canned, no need to change anything. Won't be the same, but that's not a bad thing! If they were supposed to have been canned with syrup, you'd want to add sugar to compensate.

If it seems like it's important for them to be a little softened, then you could cook them briefly in water, to do basically what canning does to them. (There's no need to actually can them in order to get that effect.) Something like 30 seconds to a couple minutes in boiling water, depending how soft you want them, and you can always add sugar afterwards to get them to the sweetness you want.

As an in-between option, you could also macerate them: toss them with sugar and let them sit for a while. That'll soften them and draw a lot of the juices out.