Swirl Spice Cake

Whisk pecans, spice mixture, brown sugar, flour, and salt in a small bowl to combine. Drizzle in butter and mix until clumps form. Set aside.
Preheat an oven to 325°F. Lightly coat an 8½x4½" loaf pan with nonstick spray. Line with parchment paper, leaving overhang on long sides. Press paper into pan, then turn over, so greased side is facing up. Whisk flour, baking soda, baking powder, and ½ tsp. salt in a medium bowl to combine.
Beat sugar and butter in the bowl of a stand mixer fitted with paddle attachment on medium-high speed, scraping down sides of bowl halfway through, until very light and fluffy, 6–8 minutes. Reduce speed to medium. With motor running, add eggs one at a time, beating to incorporate and scraping down sides of bowl after each addition. Reduce speed to low; add half of dry ingredients and mix just to combine. Add sour cream and vanilla and beat to combine. Add remaining dry ingredients and beat until incorporated.
Scrape half of batter into prepared pan. Top with streusel (yes, it will look like a lot, but use all of it!), then scrape remaining batter over. Starting at a short side of the pan and working your way to the other short side, drag a butter knife back and forth from one long side to the other through batter to marble streusel; smooth surface.
Bake cake until a tester inserted into the center comes out clean, 80–90 minutes. Transfer pan to a wire rack and let cake cool in pan 15 minutes. Run a small knife around edges of cake to loosen if needed, then, using parchment paper, lift out of pan onto rack. Peel away parchment. Let cake cool completely.
Combine powdered sugar and a pinch of salt in a small bowl, then mix in orange juice, adding up to a teaspoonful more if needed, until you have a thick but pourable icing. Drizzle over cake and let sit until icing is set before serving, about 15 minutes.
Do ahead: Cake can be baked 3 days ahead. Store airtight at room temperature.