Recently my cat was stepped on by a car. Due to that, the tail died. We only realized that after sending it to the vet. On top of that, it couldn't walk. My cat is 13 years old, but very healthy. It rarely gets sick. The vet told us that the cat needs to undergo an operation to remove its tail. However the cat couldn't go for the surgery because its sugar-level was high. Vet said probably its due to the stress. Then after the sugar-level went down, my cat successfully got its tail amputated.

Slowly it is recovering and it could walk slowly when it was at the vet.
Now, it's at home and slowly recovering. My cat could climb the stairs and jump to the bed but not jumping down. I'm wondering will she get better or this state is going to be permanent?

He will get better, no doubt.
When he was at the vet, he couldn't walk at all at first, now he is walking. He couldn't jump, but now he is jumping. So he is improving. There is no reason to suppose this improvement should suddenly stop.

He has been hit by a car, so he got severely bruised and maybe has some nerve damage. But nerves do grow back, to a certain extent, but it takes as much as a year or more.

His muscles have weakened from the accident and he will misjudge his jumps now, because he cannot jump as high or as far as he used to. Also, he has lost his tail, his main balancing organ. He will be very insecure at first, he will have to learn to calculate his jumps and find his balance again.

In the wild, he wouldn't have stood a chance, as he would not be able to catch a prey like this, but as a house cat, with a human slave to provide food, he will be fine. He will have all the time in the world to fully recover, without starving.

__________________
Jiskefet & the mognificent Dutch bunch

My little angels at the rainbow bridge

Wow. Thanks for the info. This answered my doubts!