Autofac supports open generics. You can use the following code if generics type is known at compile time:
var builder = new ContainerBuilder();
builder.RegisterGeneric(typeof(SomeInstance1<>))
.As(typeof(IGenericInterface<>));
var container = builder.Build();
var instance1 = container.Resolve<IGenericInterface<SubClass1>>();
Assert.IsInstanceOfType(typeof(SomeInstance1<SubClass1>), instance1);
If type parameter is not known until runtime (which is likely your case if you want to iterate through collection of types) then you can build your type using MakeGenericType:
var typeInRuntime = typeof (SubClass1);
var instance1 = container.Resolve(typeof(IGenericInterface<>).MakeGenericType(typeInRuntime));