The link
A dealer who is long or short S&P 500 options can hedge with S&P 500 futures (ES), with an index ETF such as SPY, with a basket of stocks, or with other options. When the hedge is futures, hedge adjustments are futures trades. Golez and Jackwerth (2012) found S&P 500 futures prices clustering at option strikes around expiration, which points to that link.
Options positioning is one force among many. News, large investors and ordinary trading can easily outweigh it on a given day.
Map the right price
The cash index and its futures are related but not equal. The gap between them, called the basis, depends on interest rates, expected dividends and time to the futures' expiry. A strike at 6,000 on the SPX index is not the same as 6,000 on the ES futures chart.
Example: if ES trades 30 points above the SPX index, an SPX level at 6,000 sits near 6,030 on the futures chart. Before you carry an options level onto a futures chart, check which contract it was converted to and how.
A pre-session read
Start with the regime at the current price (the sign of net GEX), the nearest walls, how much of the exposure expires today, and how fresh the data is. Then ask how a move or a change in volatility would alter that picture.
Caveat: a positive-gamma reading supports the idea that hedging would lean against moves. A negative-gamma reading supports the idea that it would lean with them. Neither tells you the day's direction or guarantees a range day or a trend day.