Hi: I did not use turbotax last year. Is there anyway I can upload my 1040 from previous year and pre-popoluate turbotax with (eg loss carryover, dependents etc.)?

You mean use 2018 and transfer it to 2020?  No.   Only a 2019 tax file can be transferred in to a 2020 return.

 I meant that I used another software (TaxAct) for my 2019 return- can I upload my 1040 to turbo-tax so it prepopulates my starting information for the 2020 return (e.g dependent info, carry overs etc.).  

I meant that I used another software (TaxAct) for my 2019 return- can I upload my 1040 to turbo-tax so it prepopulates my starting information for the 2020 return (e.g dependent info, carry overs etc.).  

You might be able to transfer some very basic information--but not much--depending on what kind of file you have.

How to transfer last year’s return? https://ttlc.intuit.com/questions/1900883