Is it realistic to make 5000 USD per month online? If so, what are the ways to do that?

It is really possible the best ways for this to happen is by doing Cpa sites and ecommerce.

I've seen many successful marketers make $10k per day by dropshipping.

You can read post and guides from Self Made Success - Creating Success For Entrepreneurs!

The site makes articles on ways to make money online.

And Minterest.org!

Also in making amazon affilliate sites

I would also suggest reading NicheHacks - Niche Domination Shortcuts!

You can read success story of affilliate marketers who makes $10k or more per month.