The noun nirvana can be countable or uncountable. In more general, commonly used, contexts, the plural form will also be nirvana. However, in more specific contexts, the plural form can also be nirvanas e.g. in reference to various types of nirvanas or a collection of nirvanas.

Can there's be plural?

The short answer is no. Of course, there's is the contraction for the impersonal construction there is. There is is for singular subjects; there are is for plural subjects. ... (Yes, even journalists use there's with plural nouns.)

Is a brand plural or singular?

The plural form of brand is brands.