Spurgeon was a historical premillennialist, not a futurist premillennialist. I came across the following statement of his which would indicate he was supersessionistic:
“And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.” And it is so even to this day. Here is another instance in which the Lord bade His people expect His coming, and yet at the same time told them that He would not come so long as Jerusalem should be trodden down of the Gentiles. “Until the times of the Gentiles be fulfilled” means the time when the Messiah shall gather in those Gentiles (!) unto Himself, for, when He shall appear, they shall look on Him whom they have despised, and turn to Him whom they have so long rejected (Volume 42, Luke 21:19:24)
Unless there are statements elsewhere of Spurgeon affirming Israel’s future national promises (send them to me if you find them), this statement indicates Spurgeon interpreted it as supersessionistic, rather than viewing national Israel as having restored status at the time of the fullness of the Gentles.
There were many theologians—and many Reformed theologians—in Spurgeon’s day in the 19th century that could not fathom a reconstituted nation of Israel (that changed in 1948). It would be like saying today that the Aztecs will reconstitute Mexico. So coming across texts like these they never considered that God was sovereign in this respect and would bring back Israel as a nation again; thus they interpreted them spiritually, or applied them to Gentiles, as Spurgeon did above.
Of course, I still love reading Spurgeon, to be sure, but he was fallible in some aspects of his eschatology.