Can you pay a fee to use lounge if you are traveling on a standard Alaska airlines ticket?

No. Must have first class tickets

Day pass sale was suspended the last time I visited on 7/29. A sign was posted before entry.

In Seattle and Portland they sometimes suspend day pass sales, but you do get in if you purchase a full fare First Class ticket.

You can buy a day pass. I don't know how much it is, but if you have an Alaska Airlines credit card, you can get in for $25 per person. I believe that fair is going to increase soon. But it's a great deal.