anyone can tell me how many steps there are left on each stage of the egg watch ? or how it is calculated, like if it is 1/4, 1/2 of original number of steps etc.

When it has 10+ cycles remaining to hatch: "What will hatch from this? It will take some time."
When it has 5-10 cycles remaining to hatch: "It moves around occasionally. It must be close to hatching."
When it has less than 5 cycles remaining to hatch: "It's making sounds. It's about to hatch!"

1 cycle = 255 steps. Flame Body halves that to 127 as long as it's in the party, iirc. (That, or it makes 255 steps equate to 2 cycles. I'm not sure which. Either way, it halves the time required to hatch the egg.)

Each Pokemon needs a different number of cycles to hatch; most need around 20, but some eggs such as most dragons and pseudo-legends may need as many as 40.

Search "Magikarp" in the Psydex and then click "Breeding Info" on the left. Question answered.

I think it's 5 or so. I know it's the lowest out of any Pokemon.

5120 steps is the universal average for all Pokemon. Magikarp is about one-quarter of that.