Is it viable and sustainable in search engine ranking to make my blog multi-lingual?

It's highly competitive to appear on Google search results.

No matter how lucrative Content you develop on your niche, many of your site's won't rank properly because it takes lot of continuous efforts, time and money.

So, focus on generating quality content?

You can find 90-95% of the websites are in English but all the population doesn't speak English. Means you need to translate your articles into various languages.

That will help to increase your traffic.

If you are from India, you can create content in Hindi, Tamil, Telugu, Punjabi, Kannada, malayalam, Bengali, Gujarati, Marathi. Consult web designer to make it multi-lingual and Seo friendly. It will surely increases your website's visibility in Google search.