I have a few years of back taxes to file. Is turbo tax self employed capable of this?

You can only do the last 3 years with Turbo Tax.  Online is only good for the current year.   You have to buy each year separately.  You can buy the last 3 years of Turbo Tax here,

https://turbotax.intuit.com/personal-taxes/past-years-products/

You will need a full Windows or Mac to install it on.

How to prepare a prior year return

https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-prepare-a-prior-year-tax-return/00/25984

For older returns you have to go somewhere else or get the blank forms from the IRS.   Here is the link to all the prior year IRS forms

Prior Year Forms and Instructions | Internal Revenue Service

Thanks! Though I suppose I should have indicated in the question this is for Canadian filing.

Sorry This is the USA forum.  Here is the Canada forum  

https://turbotax.community.intuit.ca/tax-help