In this particular context, only "yes, it is" is correct.

"Yes, it's ..." presupposes that the sentence continues: "Yes, it's the way to the cinema." But you wouldn't repeat all that when answering someone's question in the street, would you?

By the way, don't confuse the apostrophe ' with the accent sign ´

 

Genau darum geht es – it’s ist immer unbetont, so something else has to follow.

I explained this at length in another thread, but I'll repeat it.

You cannot contract an auxiliary verb if something understood has been deleted immediately after it. In your sentence, the 'full' version is 'Yes it is the way to the cinema.' What follows 'is' has been deleted, so you can't contract 'is'. You can say 'No it's not', however, because what follows immediately after 'is' ( in this case 'not) has not been deleted. A deletion has always taken place if the auxiliary comes last in the sentence, but not only then. For example, in the following sentence: 'I'm doing the washing-up today, and my brother is tomorrow'. You can't contract that 'is', because what immediately follows in the 'full' version of the sentence, namely 'doing the washing up', has been deleted.

Consider:

1) Can you tell me if the concert's next week (ok)

2) Can you tell me why the concert's next week (ok)

3) Can you tell me when the concert's next week (not ok)

4) Can you tell me where the concert's next week (not ok)

Here the deletions are notional, but can be recovered by giving a full answer to the question in each case.

Das Zeichen für den Apostroph liegt über dem #-Zeichen, und es erscheint beim Drücken sofort - anders als die schrägen Akzentzeichen ´ oder `

Vergleiche mal:

it´s ------> it's

doesn´t ------> doesn't