The fork is toast, though years ago we used to routinely save these. The real test is whether the steerer is bent or only the blades, but in any case, you're not likely to find anyone willing or able to straighten it properly.

The frame is probably OK and I wouldn't hesitate to ride it. The dent is in a low stress part of the tube, but even if it were a classic downtube buckle up near the headlug it would last for a long time (many thousands of miles). Eventually a crack may form but crack spreading is steel frames is a long slow process so you'll have weeks or months of notice. Odds are it'll last until something entirely else kills it off.

If it were my own bike or a family member's I wouldn't hesitate to straighten the fork (if the steerer isn't bent more than slightly), clean up the bike and keep riding it. I'd probably relegate it "B" status as a commuter or bad weather bike, or kill it off in cyclocross, not because of safety concerns, but fear of stranding if the end came far from home.