I started a business in 2017 with a partner. We incorporated a company, paid for a website, etc. The business went no where. Can i claim 50% of the expenses incurred?

How much of the loss you can declare on your tax return depends upon the specifics of the business and the nature of its failure. You can read more about it here: https://turbotax.intuit.ca/tips/losses-from-investing-in-a-failed-business-6109

If you are still unsure of what you can claim, you can contact the CRA and confirm: https://turbotax.community.intuit.ca/replies/2647704