Yes Antonline is an authorized reseller:
https://www.evga.com/products/wheretobuy.aspx.
When you get your bundle, register the GPU with EVGA:
https://www.evga.com/support/register.asp. If you are planning to do a Step Up, you'll need to upload your invoice.
Here is the info on Step Ups:
https://www.evga.com/support/stepup/.
One important thing to remember, particularly these days, is that for the Step-Up, EVGA will only credit the GPU you are stepping up from at EVGA's MSRP as listed on their product page. In other words, if you paid $1,500. for a GPU that has an EVGA MSRP of $1,000., you will get the $1,000. credit only.
Hope this helps.