19. Kontinental Hockey League trophy named for an astronaut: GAGARIN CUP. The KHL was created to further the development of hockey throughout Russia and other nations across Europe and Asia. Gagarin Cup.
26. Airport area with carousels: BAGGAGE CLAIM.
38. Planning to wed: ENGAGED. This GAG is perfectly centered in the grid.
46. One arranging gigs: BOOKING AGENT.
54. Joke used repeatedly ... and aptly found in 19-, 26-, 38-, 46- and 54-Across: RUNNING GAG. Running gags in Seinfeld.
Great progressive, or "running" placement of this clever GAG, see?
Across:
1. Game fish: BASS. First thought of the card game, Go Fish.
5. Body wrap spot: SPA. First thought was an injury. Nope.
8. Clams up, with "down": PIPES.
13. Jaunty tune: LILT. Merriam Webster defines it exactly so: "a spirited and usually cheerful song or tune," but I usually think of google dictionary's definition "a characteristic rising and falling of the voice when speaking."
14. Like a dotted note, in mus.: STAC. “Staccato” is an Italian word that means “sharply detached or separated from the other notes.” The symbol to indicate that a note or chord is to be played with a staccato articulation is a dot above or below the note (or chord).
15. Overflowing (with): AWASH.
16. Sign of spoilage: ODOR.
17. Ending with Wal: MART.
18. High-calorie cake: TORTE. Not SHORT. Could be almost anything - not many low-calorie cakes, are there?
22. Wrangler maker: JEEP.
23. Homer's neighbor: NED. The Simpson's - Ned Flanders.
24. Have grand plans: ASPIRE.
31. Pulitzer-winning author James: AGEE. For A Death in the Family. “God doesn't believe in the easy way.”
32. One of a clashing pair, perhaps: EGO. Cute.
33. Gobbled up: EATEN.
37. Moral misstep: SIN.
41. Glorifying homage: ODE.
42. Do a bakery job: KNEAD.
44. Part of pewter: TIN. Pewter contained lead as a hardener until it became widely known that lead can be toxic. It is now typically made of tin, copper, antimony, and bismuth.
45. Olympian warmonger: ARES.
50. 1965 Yardbirds hit: I'M A MAN. Not to be confused with Chicago's tune with the same name.
52. Corrosive substance: LYE.
53. Fruity beverages: ADES.
60. "The Kiss" sculptor: RODIN.
62. Old Royale 8's: REOS.
63. Jessica of "Dark Angel": ALBA.
64. "Ready Player One" novelist Ernest: CLINE.
65. Eye protector: LASH.
66. Clout: PULL.
67. Missouri River tributary: OSAGE.
68. Seeker of intel: SPY.
69. Eye woe: STYE.
Down:
1. Paperless journal: BLOG.
2. "Radames' Letter" musical: AIDA.
3. Trudge (through): SLOG.
4. Off-the-wall: STRANGE.
5. Getz of jazz: STAN. One of the greatest saxophonists of all time. Soul Eyes.
6. Pique-nique place: PARC. Not sure why google translate didn't translate parc to park on the English side.
7. Bona fide: ACTUAL. Latin = in good faith.
8. One way to stand: PAT. Interesting.
9. WWII flag-raising island: IWO JIMA.
10. Peeling gadget: PARER.
11. Big name in makeup: ESTEE.
12. Smith of Fox News: SHEP.
14. Wee bit: SMIDGEN.
20. Stephen of "Counterpart": REA. Spy thriller, on Starz.
21. "Don't text and drive" ad, e.g.: PSA. Public Service Announcement.
25. Mottled: PIED. In the case of the Pied Piper, he wore multi-colored clothing.
26. Enjoy the sun: BASK.
27. Feudin' with: AGIN. Hillbilly glossary.
28. Heredity unit: GENE.
29. Albumen container: EGG.
30. Tropical raccoon relative: COATI.
34. Zoomed: TORE.
35. Garden in a Sistine Chapel mural: EDEN.
36. Source of some tweets: NEST.
38. Genesis kingdom: EDOM.
39. Gimlet liquor: GIN. Gin, lime, and soda.
40. World's third-most spoken language: ENGLISH.
43. Belittling: ABASING.
45. Inevitable generational differences: AGE GAPS.
47. Dinghy implement: OAR.
48. Small knobs: KNURLS.
49. "We the Living" writer Rand: AYN.
50. Megastars: IDOLS.
51. __ blitz: MEDIA.
53. West Coast gas brand: ARCO.
55. Twice-monthly tide: NEAP.
56. Prone to prying: NOSY.
57. Market surplus: GLUT.
58. With skill: ABLY.
59. Powerful wind: GALE.
61. Name change indicator: NEE.