Magma BlastFusion claims to support 'structured ASIC' design which is a modern form of gate array, but I don't know much about their capability or if Talus still supports it.
The other solution is to talk to your silicon vendor and ask them what tool they recommend
Gate Ensemble is an older Cadence product from before they acquired Silicon Perspectives and the Encounter platform.
It is a dedicated gate array tool (unlike Encounter which is basically a cell based tool). Gate Ensemble is a fine gate array tool, but I don't know if Cadence still sells or supports it. Check their website or call their sales office.