A friend is coming to Vancouver, and as he has a US Visa he just got the ETA, he is visiting here from Brazil, and will enter the country via Toronto Airport.
Once here, he wants to visit Blaine and Point Roberts.
Will it be ok to come back to Canada with only the ETA?
He is allowed to travel to Canada on an eTA if he arrives by air. If he crosses to Blaine and Point Roberts on the ground, he will not be travelling by air and will require a visa to enter Canada.
He is allowed to travel to Canada on an eTA if he arrives by air. If he crosses to Blaine and Point Roberts on the ground, he will not be travelling by air and will require a visa to enter Canada.
He needs a visa to enter Canada by ground, rail, bus, ship, camel, horseback, crawling, foot, or anything that doesn't fly. Since there are no flights from Point Roberts to Canada, he cannot fly from Point Roberts to Canada. He cannot enter Canada by air.
Being admitted once does not apply to all possible entries in the future.
If you really desperately want to visit Point Roberts (there isn't anything there other than the thrill of visiting America's appendix) and Blaine, have your friend arrive Toronto, fly to Vancouver, do what you're doing in Vancouver, arrange a private charter boat between Point Roberts and Blaine, exit Canada via Point Roberts, visit Blaine, and have your friend fly home via Bellingham or Seattle. You can return to Canada whichever way tickles your fancy.